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Full text of "Malacologia"

HARVARD UNIVERSITY 




LIBRARY 



OF THE 

Museum of Comparative Zoology 



VOL 1 1962-1964 

/"2 



MALACOLOGIA 



International Journal of Malacology 
Revista Internacional de Malacologia 
Journal International de Malacologie 
Междунаролный Журнал Малакологии 
Internationale Malakologische Zeitschrift 



/I -..•^3¿. 



DATES OF PUBLICATION 

At least 50 copies of MALACOLOGIA were mailed to subscribers (including a free 
copy to the Library of Congress, Washington, D. C.) on the following dates: 

Vol. 1, No, 1 November 14, 1962 

Vol. 1, No. 2 August 7, 1963 

Vol. 1, No. 3 June 1, 1964 



-гг- 



MALACOLOGIA , VOL. 1 
CONTENTS 



J. B. BURCH 



Cytotaxonomic studies of freshwater limpets (Gastropoda: Basommatophora) 

I, The European Lake Limpet, Acroloxus lacustris 55 

Cytological studies of Planorbidae (Gastropoda: Basommatophora). 

I. The African subgenus Bulinus s.s 387 

J. B. BURCH and С M. PATTERSON 

Cytotaxonomic studied of freshwater limpets (Gastropoda: Basommatophora) 

II. The New Zealand River limpet, Latia neritoides 313 

J. B. BURCH, J. E. WILLIAMS, Y. HISHINUMA and R. NATARAJAN 

Chromosomes of some Japanese freshwater snails 

(Basommatophora: Branchiopulmonata) 403 

T. C. CHENG 

The effects of Echinoparyphium larvae on the structure of and 

glycogen deposition in the hepatopancreas of Helisoma trivolvis in 

parasite larvae 291 

A. M. CVANCARA 

Clines in three species of Lampsilis (Pelecypoda: Unionidae) 215 

H. W. HARRY 

A critical catalogue of the nominal genera and species of neotropical 
Planorbidae 33 

The anatomy of Chilina fluctuosa Gray reexamined, with prolegomena 
on the phylogeny of the higher limnic Basommatophora (Gastropoda: 
Pulmonata) 355 

H. W. HARRY and D. V. ALDRICH 

The distress syndrome in Taphius glabratus (Say) as a reaction to 

toxic concentrations of inorganic ions 283 

W. H. HEARD 

Distribution of Sphaeriidae (Pelecypoda) in Michigan, U. S. A 139 

L. HUBRICHT 

The bidentate species of Ventridens (Stylommatophora: 

Zonitidae) 417 

J. LEVER, J. C. JAGER and A. WESTERVE LD 

A new anaesthetization technique for fresh water snails, tested 

on Lymnaea stagnalis 331 

-¿¿¿- 



305 



MALACOLOGIA, VOL. 1 

A. R. MEAD 

A flatworm predator of the Giant African Snail Achatina fúlica 

in Hawaii 

J. K. NEEL and W. R. ALLEN 

The mussel fauna of the upper Cumberland Basin before its 

impoundment 427 

J. J. PARODIZ and A. A. BONETTO 

Taxonomy and Zoogeographie relationships of the South American 

Naiades (Pelecypoda: Unionacea and Mutelacea) 179 

R. POHLO 

Ontogenetic changes of form and mode of life in Tresus nuttalli 

(Bivalvia: Mactridae) 321 

I. STIGLINGH, J. A. VAN EEDEN and P. A. J. RYKE 

Contributions to the morphology of Bulinus tropicus 

(Gastropoda: Basommatophora: Planorbidae) 73 

D. W. TAYLOR and N. F. SOHL 

An outline of gastropod classification . 7 

D. W. TAYLOR, H. J. WALTER and J. B. BURCH 

Freshwater snails of the subgenus Hinkleyia (Lymnaeidae: Stagnicola) 

from the western United States 237 

H. VAN DER SCHALIE 

Mussel distribution in relation to former stream confluence in 

northern Michigan, U. S. A 227 

H. J. WALTER 

Punctation of the embryonic shell of Bulininae (Planorbidae) and 
some other Basommatophora and its possible taxonomic-phylogenetic 
implications 115 

G. L. WARMKE and L. R. ALMODOVAR 

Some associations of marine mollusks and algae in Puerto Rico 163 

С M. YAGER and H. W. HARRY 

The uptake of radioactive Zinc, Cadmium and Copper by the 

freshwater snail, Taphius glabratus 339 



-tv- 



MALACOLOGIA, VOL. 1 



TAXONOMIC AND NOMENCLATURAL CHANGES 
(New names, emendations, and new ranks) 

PELECYPODA 

Mutelacea, Parodiz and Bonetto, 1963, 186 

GASTROPODA 
(Arranged in systematic sequence after Taylor and Sohl, p 8-13) 

Architectonicacea, Taylor and Sohl, 1962, 14 
Proposed as new, but antedated by Cox, 
1960, Proc. Malac. Soc. London, 33:255. 
Cylindrobullacea, Taylor and Sohl, 1962, 17 
Acochlidioidea, Taylor and Sohl, 1962, 18 
Philinoglossoidea, Taylor and Sohl, 1962, 18 
Payettiidae, Taylor and Sohl, 1962, 18 
Acroloxacea, Taylor and Sohl, 1962, 18 
Ancylacea, Taylor and Sohl, 1962, 18 
Planorbacea, Harry, 1962, 34 
Taphiinae, Harry, 1962, 34 
Drepanotrematinae, Harry, 1962, 38 
Lymnaeacea, Taylor and Sohl, 1962, 18 
Cionellacea, Taylor and Sohl, 1962, 19 
Corillacea, Taylor and Sohl, 1962, 19 
Strophocheilacea, Taylor and Sohl, 1962, 19 
Juliacea, Taylor and Sohl, 1962, 20 
monodon, (yentridens), Hubricht, 1964, 420 
pilsbryi, {yentridens), Hubricht, 1964, 418 
Gnathodoridoidea, Taylor and Sohl, 1962, 21 
Dendronotoidea, Taylor and Sohl, 1962, 21 
Arminoidea, Taylor and Sohl, 1962, 21 
Euarminoidea, Taylor and Sohl, 1962, 21 
EoUdoidea, Taylor and Sohl, 1962, 21 
Rhodopoidea, Taylor and Sohl, 1962, 12 
Veronicellacea, Taylor and Sohl, 1962, 22 



-V- 



ri V- 



о VOL. 1 NO. 1 



OCTOBER 1962 



ifiüS. W' "^"^' ' 




. J 1962 ' 






MALACOLOGIA 



International Journal of Malacology 



Revista Internacional de Malacologia 
Journal International de Malacologie 



Международный Журнал Малакологии 



Internationale Malakologische Zeitschrift 



ALACOLOGIA 



A. GISMANN, General Editor 
19, Road 12 
Maadi, Egypt 
U.A.R. 



J. B. BURCH, Mmiaging Editor 
Museum of Zoology 
The University of Michigan 
Ann Arbor, Michigan, U.S.A. 



EDITORIAL BOARD 
SCHRIFTLEITUNGSRAT 



CONSEJO EDITORIAL 
CONSEIL DE RÉDACTION 



Редакционная Коллегия 



к. H. BARNARD 

South African Museum 

Cape Town 

Republic of South Africa 

CR. BOETTGER 

Zoologisches Institut der 
Technischen Hochschule 

Braunschweig 
Braunschweig 

Pockelsstrasse 10a 
Germany 

A. H. CLARKE, JR. 

National Museum of Canada 
Ottawa, Ontario, Canada 

C. J. DUNCAN 

Department of Zoology 
University of Liverpool 
Liverpool, England 

E. FISCHER-PIETTE 

Muséum National d'Histoire 

naturelle 
55 rue de Buff on 
Paris ye, France 

A. FRANC 

Muséum National d'Histoire 

naturelle 
55 rue de Buffon 
Paris V^, France 

K. HATAI 

Institute of Geology and 

Paleontology 
Faculty of Science 
Tohoku University 
Sendai, Japan 



N. A. HOLME 

Marine Biological Association 

of the United Kingdom 
The Laboratory, Citadel Hill 
Plymouth, Devon, England 

G. P. KANAKOFF 

Los Angeles County Museum 

900 Exposition Boulevard 

Los Angeles 7, California, U.S.A. 

A. M. KEEN 

Department of Geology 
Stanford University 
Stanford, California, U.S.A. 

Y. KONDO 

Bernice P. Bishop Museum 
Honolulu 17, Hawaii, U.S.A. 

N. MACAROVICI 

Laboratoire de Géologie 
Université "Al. I. Cuza" 
laçi, Romania 

D. F. McMICHAEL 

The Australian Museum 
College Street 
Sidney, Australia 



J. E. MORTON 

Department of Zoology 
The University of Auckland 
Auckland, New Zealand 



W. L. PARAENSE 

Instituto Nacional de 
Endemias Rurais 
Caixa Postal, 2113 
Belo Horizonte 
Minas Gérais, '3rasil 

J. J. PARODIZ 

Carnegie Museum 
Pittsburg 13, Pennsylvania, 

U.S.A. 

R. D. PURCHON 

Department of Zoology 
University College of Ghana 
Legon, Accra, Ghana 

S. G. SEGERSTRALE 
Zoological Museum of 

Helsinki University 
P.-Rautatiekatu 13 
Helsinki, Finland 

J. STUARDO 

Departamento de Zoología 
Instituto Central de Biología 
Universidad de Concepción 
Cas. 301, Concepción, Chile 

W.S.S. VAN DER FEEN - VAN 
BENTHEM JUTTING 

Zoologisch Museum 

Amsterdam, The Netherlands 

CM. YONGE 

Department of Zoology 
The University 
Glasgow, Scotland 



MALACOLOGIA was established with the aid of a grant 
(NSF-G24250) from the National Science Founda- 
tion, Washington, D.C, U.S.A. 

MALACOLOGIA wurde unter Beihilfe einer Unterstü- 
tzung (NSF-G24250) der National Science Founda- 
tion, Washington, D.C, U.S.A., gegründet. 

MALACOLOGIA fut établi avec l'aide d'une subven- 
tion (NSF-G24250) de la National Science Founda- 



tion, Washington, D.C, U.S.A. 

MALACOLOGIA fue establecida con la ayuda de una 
subvención (NSF-G24250) de la National Science 
Foundation, Washington, D.C, U.S.A. 

Журнал МАЛАК0.Т10ГИЯ был подготовлен к изданию 
при помощи субсидии (NSF -G24250) от Госуд- 
арственного научного общества в Вашингтоне, 
США. 



MALACOLOGIA, AN INTERNATIONAL JOURNAL OF MALACOLOGY 



Ы 



The founders of MALACOLOGIA hope 
that this new journal will fill the needs of 
those workers in different countries who 
have found it difficult to get long articles 
or monographs published. They also aim 
to create an international friendly inter- 
est among all those who favour exchange 
of moUuscan information. A definite need 
for a journal of high quality, that would 
be devoted to the multiple aspects of the 
study of mollusks, and would publish 
promptly long manuscripts has been re- 
cognized for quite some time in the United 
States, especially by those active at the 
major malacological research institutions . 
A small group of malacologists, while 
attending the annual meeting of the Ameri- 
can Malacological Union in June 1961, 
discussed the feasibility of promoting such 
a journal on an international basis. It 
seemed to them that such a journal would 
provide not only an outlet to all those 
requiring it, but would also promote an 
exchange of ideas between the continents 
and assist in the speedier integration of 
knowledge by providing multilingual publi- 
cation and abstracting. 

It seemed prudent to test the extent of 
possible support for such a journal. Ac- 
cordingly, a questionnaire was submitted 
to 192 malacologists and other zoologists 
workingwith mollusks at home and abroad. 
The group to which it was sent is broadly 
representative of malacology all over the 
world; it is formed of the members of 
various zoological societies, of scientists 
who are carrying on research, who ac- 
tively publish and who are associated with 
institutions granting advanced degrees. 

The respond ^ was encouraging: 80% of 
the questioruaires were returned; 92% of 
those who replied favoured establishment 
of a ne- journal as proposed, and many 
favoured it strongly; 6% were undecided 
and 2% opposed the establishment of such 
.ajournai. Many replies went beyond 
merely filling out the questionnaire and 
contributed thoughtful advice. On the ba- 
sis of the estimated number of subscrip- 



tions obtained, establishment of a self- 
supporting journal seemed practical. 

The funds for the establishment of 
MALACOLOGIA, and for its maintenance 
during the first years of operation, were 
obtained from a grant made by the Na- 
tional Science Foundation, Washington, 
D, C, U. S. A. Since such grants are 
usually awarded only to bona fide non- 
profit organizations, the Institute of Mala- 
cology, which meets the requirements, 
was legally established. The founding 
group of the Institute of Malacology is 
responsible for selecting editors and for 
making such occasional policy decisions 
as may be necessary for the operation 
and publishing of MALACOLOGIA. Pre- 
sent members of the Institute of Mala- 
cology are listed on the inside front cover 
of this issue. 

The purposes and goals of MALACO- 
LOGIA may be summarized as follows: 
1) To publish promptly contributions too 
long for most of the present malacologi- 
cal journals. 2) To maintain scholarly 
standards and continuity of publication as 
well as editing by an editorial board. 
The present Editorial Board will be in- 
creased by the addition of a sufficient 
number of editors to ensure coverage of 
major areas of specialization and of all 
countries. To make sure of originality 
of research and technical competence, 
each manuscript will be reviewed by two 
or more editors. 3) To assemble in one 
publication papers that otherwise might 
be scattered in a number of different 
scientific journals, in the hope of has- 
tening a fruitful exchange of information 
and ideas within the field of malacology. 
4) To promote cooperation and to stimu- 
late research in malacology through the 
medium of an international journal. 



Elmer G. Berry 
J. B. Burch 
Melbourne R.Carriker 
Anne Gismann 



Robert Robertson 
Allyn G. Smith 
Norman F. Sohl 
Dwight W. Taylor 



(1) 



MALACOLOGIA, EINE INTERNATIONALE MALAKOLOGISCHE ZEITSCHRIFT 



Die Gründer von MALACOLOGIA hoffen 
mit dieser neuen Zeitschrift jenen For- 
schern in verschiedenen Ländern von 
Nutzen zu sein, die bei der Veröffent- 
lichung längerer Abhandlungen oder Mono- 
graphien auf Schwierigkeiten gestossen 
sind. Gleicherweise bezwecken sie eine 
freundliche Anteilnahme in all denjenigen 
anzuregen denen ein Meinungsaustausch 
in Sachen der Weichtierkunde zwischen 
den Nationen wünschenswert erscheint. 
Dass in den Vereinigten Staaten von 
Amerika zweifelsohne Nachfrage nach 
einem Qualitätsblatt besteht, welches sich 
den mannigfaltigen Gesichtspunkten der 
Weichtierforschung widmen und längere 
Manuskripte raschestens veröffentlichen 
würde, wurde besonders von den an den 
wichtigeren malakologischen Forschungs- 
instituten wirkenden Wissenschaftlern 
längst erkannt. Bei der alljährlichen 
Zusammenkunft der Amerikanischen Mala- 
kologischen Union, im Juni 1961, besprach 
eine kleine Gruppe von Malakologen die 
Aussichten, auf internationaler Basis eine 
derartige Zeitschrift zu errichten. Man- 
war sich einig, dass eine solche nicht 
nur denjenigen, die eines Ausdrucksmittels 
bedurften, dienlich sein würde, sondern 
dass ein Gedankenaustausch zwischen den 
Kontinenten im allgemeinen von Vorteil 
wäre und dass, durch Darbietung ver- 
schiedensprachiger Veröffenlichungen 
und vor allem Zusammenfassungen in 
mehreren Sprachen, der Integration un- 
seres Wissens eine fruchtbringende Be- 
schleunigung erteilt werden würde. 

Es schien daher angebracht das Aus- 
mass der zu erwartenden Anteilnahme an 
einer solchen Zeitschrift zu ergründen. 
Fragebögen wurden an 192 in- und aus- 
ländische Malakologen oder andere sich 
mit Weichtieren befassende Zoologen aus- 
geschickt. Der befragte Kreis, welcher 
über die Welt hin mehr oder minder für 
Malakologie repräsentatif ist, besteht teils 
aus Mitgliedern verschiedener malako- 
logischer Vereine, teils aus rege for- 
schenden und veröffentlichenden Gelehrten, 
sowie aus solchen die an Instituten tätig 
sind welche höhere Diplome erteilen. 



Der Widerhall war recht ermutigend: 
80% der ausgesandten Rundfragen wurden 
beantwortet; 92% der Antworten waren 
zustimmend, manche darunter sogar äus- 
serst bejahend; 6% der Befragten waren 
unentschieden und 2% waren dagegen. 
Viele der Antworten gingen weit über den 
Rahmen des Fragebogens hinaus und 
brachten wohldurchdachte Ratschläge. Auf 
Grund der voraussichtlichen Abonnenten- 
zahl erschien die Gründung einer auf 
eigenen Füssen stehenden Zeitschrift 
durchaus im Bereich des Möglichen. 

Die erstmaligen Mittel für die Grün- 
dung von MALACOLOGIA, sowie ein Be- 
triebskostenzuschuss für die ersten Jahre, 
sind durch eine Schenkung der ''National 
Science Foundation" in Washington, D.C. 
gedeckt. Da derartige Subventionen im 
allgemeinen nur bona fide nicht ertrag- 
bringenden Organisationen gewährt wer- 
den, wurde vorerst, um den bestehenden 
Bedingungen zu entsprechen, ein "Institut 
für Malakologie" (Institute of Malacology) 
gesetzesgemäss gegründet. Seine Be- 
gründer haben die gegenwärtige Schrift- 
leitung gewählt und treffen allfällige zur 
Handhabung und Veröffentlichung von MA- 
LACOLOGIA erforderlichen Entscheidun- 
gen. Die gegenwärtige Mitgliedschaft des 
Institutes ist auf der Innenseite des vor- 
deren Umschlagsblattes aufgeführt. 

MALACOLOGIAs Ziele und Bestrebun- 
genkönnen nun wie folgt zusammengefasst 
werden; es ist beabsichtigt: 1) Beiträge, 
die für die meisten bestehenden mala- 
kologischen Blätter zulange sind, schnell- 
stens zu veröffentlichen. 2) Mittels eines 
auf breiter Basis gewählten Redaktion- 
sausschusses das wissenschaftliche Niveau 
der Zeitschrift, die Kontinuität ihrer Ver- 
öffentlichungwie auch einer angemessenen 
Schriftleitung zu gewährleisten; er soll, 
um den verschiedenen Spezialisierungs- 
gebieten und den sprachlichen und regiona- 
len Anforderungen gerecht zu werden, der 
bestehende Redaktions rat durch Aufnahme 
einer genügenden Anzahl von Schriftleitern 
erweitert werden. Um sich der Ursprüng- 
lichkeit des Forschungsstoffes wie auch 
der technischen Kompetenz der Arbeiten 



MALACOLOGIA 



zu versichern, wird jedes Manuskript 
von zumindest zwei oder auch mehreren 
Schriftleitern rezensiert werden. 3) Es 
sollen fernerhin in einer einzigen Ver- 
öffentlichung Arbeiten vereinigt werden 
die sonst in verschiedenen wissenschaft- 
lichen Zeitschriften zerstreut erscheinen 
würden, wobei die Beschleunigung frucht- 
barer Wechselbeziehungen im Bereiche 
der Malakologie zu erhoffen ist. 4) Es 



soll auf diesem Gebiete, mittels einer 
internationalen Zeitschrift, die Zusam- 
menarbeit gefordert und die Forschung 
angeregt werden. 

Eimer G. Berry Robert Robertson 

J. B. Burch Allyn G. Smith 

Melbourne R. Carriker Norman F. Sohl 

Anne Gismann Dwight W. Taylor 



MALACOLOGIA, UN JOURNAL INTERNATIONAL DE MALACOLOGIE 



Les fondateurs de MALACOLOGIA es- 
pèrent par ce nouveau journal combler 
une lacune et être utile à tous ceux qui, 
dans les divers pays, sont venus à Ren- 
contre de difficultés dans la publication 
de leurs articles longs ou de leurs mono- 
graphies. En outre, ils envisagent créer 
une entente amicale parmi tous ceux qui 
regardent avec faveur un échange d'in- 
formation dans le domaine de la malaco- 
logie. 

Le fait qu'il existe certainement une 
demande pour un journal de haute quali- 
té, dévoué aux multiples aspects de l'étude 
des mollusques et publiant promptement 
des manuscripts longs, a été reconnu 
depuis quelque temps déjà aux États Unis 
d'Amérique, particulièrement parmi le 
personnel des principaux centres de re- 
cherches malacologiques. En Juin 1961, 
un petit groupe de malacologues, parti- 
cipant à la réunion annuelle de l'Union 
Malacologique Américaine, discuta les 
possibilités de fonder un journal de ce 
genre sur une base internationale. Il 
leur parut qu'un pareil journal non seule- 
ment fournirait un débouché à ceux qui 
en auraient besoin, mais servirait aussi 
à avancer un échange d'idées entre les 
continents et, en fournissant une publi- 
cation et surtout une résumation multi- 
linguale, favoriserait en même temps une 
intégration plus rapide de notre savoir. 

Il semblait alors opportun de mettre à 
l'épreuve l'étendue du support à attendre 



pour un journal pareil. Un questionnaire 
fut donc soumis a 192 malacologues ou 
autres zoologues s'occupantde mollusques. 
Le groupe questionné - plus ou moins re- 
présentatif en malacologie de parle mon- 
de - comprend des membres de diverses 
sociétés malacologiques, des savants soit 
engagés en recherches, soit publiant ac- 
tivement, ainsi que du personnel associé 
à des institutions scientifiques conférant 
des degrés supérieurs. 

L'écho que provoqua notre enquête fut 
encourageant: réponse fut faite à 80% des 
questionnaires envoyés; 92% de ces ré- 
ponses étaient en faveur d'un nouveau 
journal tel que proposé et certaines d'en- 
tre elles l'étaient fortement; 6% des cor- 
respondants se montrèrent indécis tandis 
que 2% étaient opposés à l'idée. Certaines 
réponses dépassaient même de beaucoup 
le cadre du questionnaire et apportèrent 
des conseils réfléchis. A la base du nom- 
bre estimé d'abonnements, l'établisse- 
ment d'un journal subsistant par ses 
propres moyens semblait faisable. 

Les fonds pour Г établissement premier 
de MALACOLOGIA ainsi que pour les 
frais d'entretien pendant les quelques 
premières années proviennent d'une do- 
nation de la "National Science Founda- 
tion" a Washington, D. C. Parceque, 
d'habitude, de telles subventions ne sont 
accordées qu'à des organisations de bonne 
foi non-commercielles, et pour faire face 
aux exigences de la situation, "l'Institut 



MALACOLOGIA 



de Malacologie" (Institute of Malacology) 
fut d'abord légalement établi. C'est le 
groupe fondateur de cet institut qui est 
en ce moment responsable du choix des 
décisions nécessaires à l'opération et à 
la publication de MALACOLOGIA. Les 
membres actuels de l'institut sont cités 
sur la face intérieure frontale de la cou- 
verture. 

Les intentions et les buts de MALA- 
COLOGIA peuvent être résumés comme 
suit: 1) De publier promptement des con- 
tributions trop longues pour la plupart 
des journaux malacologiques contempo- 
rains. 2) De maintenir un niveau sci- 
entifique élevé ainsi qu'une continuité et 
de publication et de rédaction par un con- 
seil de rédaction, dont le nombre de mem- 
bres sera suffisamment augmenté pour 
faire justice aux aires majeures de spé- 



cialisation et aux exigences des diverses 
langues et régions. Afin d'assurer l'ori- 
ginalité des recherches faites et de la 
compétence technique de l'oeuvre, chaque 
manuscript sera passé en revue par aux 
moins deux rédacteurs. 3) D'assembler 
en une unique publication des traveaux 
qui, autrement, seraient dispersés parmi 
un nombre de journeaux scientifiques di- 
vers dans l'espoir d'accélérer ainsi 
un échange fractueux d'informations et 
d'idées sur le terrain de la malacologie. 
4) De stimuler la cooperation et les re- 
cherches en malacologie par la voie d'un 
journal international. 



Elmer G. Berry 
J. B. Burch 
Melbourne R. Carriker 
Anne Gismann 



Robert Robertson 
Allyn G. Smith 
Norman F. Sohl 
Dwight W. Taylor 



MALACOLOGIA, UNA REVISTA INTERNACIONAL DE MALACOLOGIA 



Los fundadores de MALACOLOGIA abri- 
gan el deseo de que esta nueva publica- 
ción pueda satisfacer la necesidad de los 
investigadores de diferentes países que 
encuentran dificultad en dar a conocer 
artículos y monografías de cierta exten- 
sion. Tiene, ademas, el propósito de 
crear un amistoso interés internacional 
entre quienes favorecen al intercambio 
de información sobre moluscos entre los 
países. La necesidad de una revista al- 
tamente calificada, dedicada a los múlti- 
ples aspectos del estudio délos moluscos, 
con publicación inmediata de largos manu- 
scritos, viénese reconociendo desde hace 
tiempo en los Estados Unidos, especial- 
mente por aquellos que actúan en insti- 
tuciones de investigación malacológica 
mayor. Un pequeño grupo de malacólo- 
gos, asistentes al mitin anual de la Union 
Malacológica Americana en Junio de 1961, 
discutieron la practicabilidad de promover 
la publicación de una revista sobre base 
internacional. Los iniciadores estimaron 
que tal revista sería, no solamente un 



medio para dar salida a los trabajos de 
aquellos que los requieren, sino también 
favorecer un intercambio de ideas entre 
los continentes y ayudar la integración 
más rápida del conocimiento, con la pro- 
visión de publicaciones y resúmenes mul- 
tilingues. 

Pareció prudente comenzar por probar 
la posibilidad de soporte para tal revista. 
Un cuestionario se sometió a la crítica 
de 192 malacólogos, y otros zoólogos que 
trabajan sobre moluscos en el país y en 
el extrangero, un grupo que es amplia- 
mente representativo de la malacologia 
en todo el mundo, miembros de diversas 
sociedades zoológicas, científicos que in- 
vestigan y publican activamente. 

La acogida fue promisoria: 80% do los 
cuestionarios fueron devueltos: 92% re- 
spondieron favorablemente; 6% indecisos, 
y solo 2% se opusieron a la publicación 
de la revista. Muchas respuestas so- 
brepasaron el cuestionario, contribuyendo 
con sugestiones y consejos. En base al 
estimado número de subscripciones ob- 



MALACOLOGIA 



tenidas, la revista parecía automática- 
mente soportada. 

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cubierta frontal interna de este ejemplar. 

Les propósitos de MALACOLOGIA son 
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artículos y monografías que resultan muy 
extensos para la mayoría de las revistas 
actualmente en publicación. 2) Mantener 



standards de escuela, continuidad de pub- 
licación, y editoriales. El consejo edi- 
torial será aumentado con un número su- 
ficiente de editores para cubrir las areas 
mayores de especialisación en todos los 
países. A fin de asegurar la originalidad 
de investigación y competencia técnica, 
cada manuscrito sera revisado por dos o 
más editores. 3) Agrupar en una publi- 
cación, travajos que de otra mènera pue- 
den dispersarse en numerosas y diferentes 
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formación e ideas dentro del campo inala- 
cológico. 4) Promover la cooperación y 
estimular estudios en malacología, medi- 
ante un órgano internacional. 



Elmer G. Berry 
J. В. Burch 
Melbourne R. Carriker 
Anne Gismann 



Robert Robertson 
AUyn G . Smith 
Norman F. Sohl 
Dwight W. Taylor 



* 



MALACOLOGIA, 1962, 1(1): 7-32 



AN OUTLINE OF GASTROPOD CLASSIFICATION^'^ 

D. W. Taylor and N. F. Sohl 
и. S. Geological Survey, Washington, D. С 



ABSTRACT 

This outline is a compilation of familial and super- familial classification, 
primarily from the "Handbuch der Paläozoologie" (Wenz and Zilch) and the 
"Treatise on Invertebrate Paleontology" (Knight and others). These summaries 
have been supplemented, especially in the shell-less groups, to make the classi- 
fication as nearly consistent as practicable. Numbers of genera and subgenera 
are listed for each family, but genera described after publication of the principal 
sources have been included only rarely, so that the relative size of the groups 
is indicated only in a general way. Annotations include references to the more 
important taxonomic groups and explanations of the ways in which divergent 
classifications have been reconciled. 

Gastropods (7324 genera and subgenera) are divided into the two subclasses 
Streptoneura and Euthyneura. Although the Streptoneura (4218 genera and sub- 
genera) are larger, they are divided into only 3 orders. The Euthjoieura (3106 
genera and subgenera) are more diverse structurally and are divided into 14 orders. 



Several recent publications have sum- 
marized the classification of large parts 
of the class Gastropoda. The Treatise 
on Invertebrate Paleontology (Knight and 
others, 1960) covers living and fossil 
Archaeogastropoda and other Paleozoic 
gastropods. Zilch (1959-60) has dealt with 
living and fossil shelled Euthyneura. Wenz 
(1938-44) is the most recent comprehen- 
sive source on living and fossil post- 
Paleozoic mesogastropods and neogastro- 
pods. 

We have compiled an outline of gastro- 
pod classification from these sources and 
supplemented it by the works of others as 
indicated in the notes. This classification 
extends only to the family level. We have 
been conservative in recognizing families 
and superfamilies proposed in sources 
other than these basic works. Other gen- 
eral and recent works which we have con- 
sidered are those by Korobkov (1955), 
Pchelintsev and Korobkov (1960), and 
Termier and Termier (1952). 

In the following outline of classification 
the number of genera and subgenera is 
listed for each family. These numbers 



are taken from the sources mentioned 
above, with modifications as indicated. 
Genera described since these works were 
published have rarely been included. This 
classification is therefore out of date to 
varying degrees, and includes many of 
the weaknesses of the general works 
quoted. 

In some cases, especially among the 
Neogastropoda, there has been rather uni- 
form disagreement as to Wenz' s familial 
classification. In as much as no recent 
monographic treatment exists for these 
groups we have retained Wenz' s classifi- 
cation but have listed the common alter- 
natives in parentheses. 

The relative size of the orders based 
on numbers of their genera and subgenera 
is shown in figures 1 and 2 . Our classi- 
fication, including both living and fossil 
groups, is the basis of figure 1. Thiele' s 
(1929-35) classification, including living 
forms only, is the basis of figure 2 . The 
only obvious difference between the graphs 
is that in figure 2 the Stylommatophora 
have increased, primarily at the expense 
of the Archaeogastropoda. 



^Publication authorized by the Director, U. S. Geological Survey 

^Separates of this paper may be obtained from the Managing Editor of MALACOLOGIA at cost 
price. 

(7) 



TAYLOR AND SOHL 





FIG. 1. Relative size of subclasses and orders 
of gastropods, recent and fossil. Arcs are pro- 
portional to numbers of genera given in this 
paper. 4, Parasita and Entomotaeniata. 5, 
Cephalaspidea, Acochlidioidea, and Philinoglos- 
soidea, 6, Thecosomata. 9, Sacoglossa. 10, 
Anaspidea. 11, Gymnosomata. 12, Notaspidea. 
14, Soleolifera, 

In general we believe that the families 
and superfamilies throughout the gastro- 
pods correspond to about the same degree 
of morphological difference, with the ex- 
ception of the Archaeogastropoda, where 
many of the families and superfamilies 
have relatively few genera. This order 
has been more finely divided than others. 

In accepting the subdivision of the gas- 
tropods into Streptoneura and Euthyneura, 
we have abandoned the familiar three- 
fold division into Prosobranchia, Opistho- 
branchia, and Pulmonata. We have fol- 
lowed Boettger's(1955) andZilch's (1959- 
60) fusion of opisthobranchs and pul- 
monates into the Euthyneura of Spengel. 
Streptoneura is preferable to Prosobran- 
chia for the remaining gastropods because 
of the similar derivation of the name. 



CLASSIFICATION 

Asterisks denote groups that are known 
only as fossils. 

The left-hand column indicates the num- 



FIG. 2. Relative size of subclasses and orders 
of recent gastropods. Arcs are proportional to 
numbers of genera in Thiele' s (1929-35) classi- 
fication. Numbers as in Fig. 1. 

ber of genera and subgenera for each 
family. The right-hand column indicates 
totals for categories above family. 

Class GASTROPODA 7324 

Subclass STREPTONEURA 4218 

1. 



Order Archaeogastropoda 






(note 1) 




ИЗО 


*Superfamily Helcionellacea 




4 


*Helcionellidae 


1 




*Coreospiridae 


3 




*Superfamily Bellerophontac 


ea 




(note 1) 




53 


*Cyrtolitidae 


6 




*Sinuitidae 


14 




* Bellerophontidae 


33 




*Superfämily Macluritacea 




17 


*Onychochilidae 


10 




*Macluritidae 


7 




*Superfamily Euomphalacea 




42 


*Helicotomidae 


8 




*Euomphalidae (note 2) 


26 




*Omphalotrochidae 


5 




*VVeeksiidae (note 2) 


3 




Superfamily Pleurotomariac( 


эа 




(note 1) 




149 


*Sinuopeidae 


13 




♦Raphistomatidae 


21 




*Eotomariidae 


26 




*Lophospiridae 


7 




*Luciellidae 


5 




* Phanerotrematidae 


3 




*Gosseletinidae 


14 





OUTLINE OF GASTROPOD CLASSIFICATION 



*Euomphalopteridae 3 

*Portlockiellidae 4 

*Catantostomatidae 1 

*Porcelliidae 3 

*Rhaphischismatidae 1 

*Phyinatopleuridae 10 

*Polytremariidae 2 

*Laubellidae 1 

*Schizogoniidae 2 

*Zygitidae 1 

*Kittlidiscidae 1 

*Temnotropidae 1 

Pleurotomariidae 11 

*Trochotomidae 3 

Scissurellidae 5 

Haliotidae 11 

*Superfamily Trochonematacea 7 

*Trochonematidae 7 

Superfamily Fissurellacea 56 

Fissurellidae 56 

Superfamily Patellacea 55 

*Metoptomatidae 3 

*Symmetrocapulidae 2 

Acmaeidae 29 

Patellidae 16 

Lepetidae 5 

Superfamily Cocculinacea 10 

Cocculinidae . 4 

Lepetellidae 6 

*Superfamily Platyceratacea 26 

*Holopeidae 13 

*Platyceratidae 13 

* Superfamily Microdom atacea 10 

*Microdomatidae 5 

*Elasmonematldae 5 

*Superfamily Anomphalacea 9 

*Anomphalidae 9 

*Superfamily Oriostomatacea 9 

*Oriostomatidae 3 

*Tubinidae 6 

Superfamily Trochacea 399 

Trochidae 231 

*Ataphridae 7 

Stomatellidae 12 

Turbinidae 91 

Skeneidae (note 3) 46 

Phasianellidae (note 4) 9 

*Velainellidae 1 

Orbitestellidae 2 

Superfamily Neritacea 162 

*Plagiothyridae 3 

Neritopsidae 17 

*Dawsonellidae 1 

Neritidae 67 

Helicinidae 60 
*Grangerellidae (note 5) 3 

*Deianiridae 1 

Phenacolepadidae 5 

Hydrocenidae 4 

Titiscaniidae 1 

* Superfamily Murchi- 

soniacea 35 

*Murchisoniidae 27 



*Plethospiridae 8 
*Superfamily Clisospiracea 

*Clisospiridae 5 
*Superfamily Pseudophoracea 

*Planitrochidae 6 

*Pseudophoridae 9 
* Superfamily Craspedosto- 
m atacea 

*Craspedostomatidae 8 

*Codonocheilidae 6 

*Crossostomatidae 2 
*Superfamily Palaeotrochacea 

*Palaeotrochidae 4 

*Paraturbinidae 3 
*Superfamily Amberleyacea 

*Platyacridae 5 

*Cirridae 8 

*Amberleyidae 10 

*Nododelphinulidae 5 
2. Order Mesogastropoda 

Superfamily Cyclophoracea 
(note 6) 

Cyclophoridae 61 

Maizaniidae 1 

Poteriidae ц 

Pupinidae 26 

Cochlostomatidae 39 
Superfamily Viviparacea 
(note 6) 

Viviparidae 30 

Ampullariidae (Pilidae) 17 
Superfamily Valvatacea 

Valvatidae 14 
Superfamily Littorinacea 

Lacunidae 28 

Littorinidae 30 

* Purpurinidae 18 

Pomatiasidae 16 

Chondropomidae 66 
Superfamily Rissoacea 
(note 7) 

Hydrobiidae (note 8) 103 

Truncatellidae 16 

Hydrococcidae 1 

Stenothyridae 3 
Bithyniidae (Bulimidae) 

(note 9) 16 

Iravadiidae 2 

Micromelaniidae 47 
Rissoidae (note 9A) 104 
Assimineidae (Syncera- 

tidae)(note 8) 37 

Aciculidae (note 10) 8 
Vitrinellidae (Adeorbidae, 

Tornidae) (note 11) 55 

Skeneopsidae (note 12) 3 

Omalogyridae (note 12) 3 

? Trachysmidae 1 

-Pissoellidae (note 12) 4 
Cingulopsidae (notes 12, 

13) 1 

? Choristidae 2 

? Trochaclisidae 1 



15 



16 



28 

1969 
146 



47 



14 

158 



407 



10 



TAYLOR AND SOHL 



*Superfamily Subulitacea 




17 


Trichotropididae 


25 


*Subulitidae 


14 




Capulidae 


9 


*Meekospiridae 


3 




Calyptraeidae 


19 


*Superfamily Loxonematacea 




65 


Xenophoridae (note 22) 


7 


* Loxonematidae 


7 




Superfamily Lamellariacea 




* Palaeozygopleuridae 


2 




Lamellariidae 


14 


* Pseudozygopleuridae 


14 




Eratoidae (note 22A) 


21 


*Zygopleuridae 


12 
25 




,/ , Pseudosacculidae 


_J:= 


*Coelostylinidae 


\> ''^^ i^ Asterophilidae 


1 


*Spirostylidae 


5 




0,,' ' Ctenosculidae 

^ Superfamily Cypraeacea 


1 


*Superfamily Pseudomelaniacea 








(note 14) 




20 


(note 2 2 A) 




* Pseudomelaniidae 


16 




Cypraeidae 


68 


*Glauconiidae 


4 




Ovulidae (Amphiperatidae) 




Superfamily Architectonicacea 






(note 23) 


38 


(note 15) 




27 


Superfamily Atlantacea 




Architectonicidae (Solariidae) 


25 




Atlantidae 


5 


? Omalaxidae 


2 




Carinariidae 


4 


Superfamily Cerithiacea 




410 


Pterotracheidae 


2 


Turritellidae (note 16) 


40 




Superfamily Naticacea 




Mathildidae (note 15) 


15 




Naticidae 


75 


Vermetidae (note 16) 


10 




Superfamily Tonnacea 




Caecidae 


12 




Cassididae 


25 


Syrnolopsidae (note 7) 


5 




Cymatiidae 


35 


Thiaridae (Melaniidae) 






Bursidae 


11 


(note 17) 


121 




Tonnidae (note 24) 


6 


Melanopsidae 




Ficidae 


9 


Pleuroceridae (note 21) 






3. Order Neogastropoda (note 25) 




? Abyssochrysidae 


1 




Suborder Stenoglos sa 




Planaxidae 


9 




Superfamily Muricacea 




Modulidae 


4 




Muricidae (includes 




* ? Brachytremidae 


2 




Thaisidae) (note 25) 


134 


* ? Eustomidae 


2 




Magilidae (Corallio- 




*Procerithiidae 


33 




philidae) 


20 


Potamididae 


37 




Superfamily Buccinacea 




Diastomidae 


11 




Pyrenidae (Columbellidae] 


1 50 


Cerithiidae (note 14) 


56 




Buccinidae ^ 




Cerithiopsidae 


32 




Neptuneidae > 


175 


Triphoridae (note 18) 


19 




Buccinulidae J 




Seguenziidae (note 19) — 


1 




Melongenidae (Galeodidae) 


\ 


Superfamily Epitoniacea (Scalacea) 




(note 26) 


27 


(note 19 A) 




110 


Nassariidae (Nassidae) 




Epitoniidae (Scalidae) 






(note 25) 


68 


(note 19 A) 


103 




Fasciolariidae (includes 




Janthinidae 


7 




Fusinidae) 


66 


Superfamily Eulimacea (Melanel 


lacea) 


Superfamily Volutacea 




(note 20) 




48 


Olividae 


53 


Aclididae 


7 




Vasidae (Xancidae) 


26 


Eulimidae (Melanellidae) 


26 




Harpidae 


4 


Paedophoropodidae 


. 1 




Volutidae 


97 


Stiliferidae 


Í4 




Cancellariidae 


48 


Superfamily Strombacea 






Marginellidae 


24 


(note 22) 




92 


Suborder Toxoglossa 




Struthiolariidae 


7 




Superfamily Mitracea 




Aporrhaidae 


32 




Mitridae (note 25) 


31 


*Colombellinidae 


6 




Superfamily Conacea 




Strombidae 


47 




Turridae 


246 


Superfamily Hipponicacea 




32 


Conidae 


25 


Fossaridae 


23 




Terebridae 


25 


Vanikoridae (Naricidae) 


1 








Hipponicidae (Amaltheidae) 


8 




Subclass EUTHYNEURA (note 27) 




Superfamily Calyptraeacea 










(note 21) 




60 


4. Order Entomotaeniata (note 28) 





38 



106 



11 



75 
86 



1119 
792 
154 



386 



252 



327 
31 

296 



3106 
171 



OUTLINE OF GASTROPOD CLASSIFICATION 



11 



*Superfamily Nerineacea 




36 


*Ceritellidae 


5 




*Nerineidae 


13 




*Nerinellidae 


10 




*Itieriidae 


8 




Superfamily Pyramidellacea 




135 


Pyramidellidae 


131 




*Streptacididae 


4 




5. Order Parasita (note 20) 




5 


Entoconchidae 


2 




Enteroxenidae 


3 




6. Order Cephalaspidea (note 29) 




158 


Superfamily Acteonacea 




66 


Acteonidae 


43 




*ActeonelIidae (note 30) 


7 




Ringiculidae 


12 




Hydatinidae 


4 




Superfamily Philinacea 




44 


Scaphandridae 


28 




Philinidae 


9 




Aglajidae 


3 




Gastropteridae 


1 




Runcinidae 


3 




Superfamily Diaphanacea 




8 


Diaphanidae (note 31) 


7 




Notodiaphanidae 


1 




Superfamily Bullacea 




39 


Bullidae 


5 




Atyidae 


24 




Retusidae 


10 




Sup)erfamily Cylindrobullacea 






(note 32) 




1 


CylindrobuUidae 


1 




7. Order Acochlidioidea (note 33) 




7 


Acochlidiidae 


1 




Hedylopsidae 


2 




Microhedylidae 


4 




8. Order Philinoglossoidea (note 34) 




2 


Philinoglossidae 


2 




9. Order Thecosomata 




23 


Superfamily Spiratellacea 




17 


Spiratellidae 


2 




Cavolinidae 


15 




Superfamily Peraclidacea 




6 


Peraclididae 


1 




Procymbuliidae 


1 




Cymbuliidae 


3 




Desmopteridae 


1 




10. Order Basommatophora (note 35) 




230 


Superfamily Siphonariacea 




23 


Trimusculidae 


1 




Siphonariidae (note 36) 


20 




* ? Acroreidae 


2 




Superfamily Amphibolacea 






(note 36A) 




2 


Amphibolidae 


2 




Superfamily EUobiacea 




57 


Ellobiidae (note 6) 


55 




Otinidae 


2 




Superfamily Unnamed (note 3 


7) 


3 


Chilinidae 


1 




Latiidae 


1 




♦Payettiidae (note 37) 


1 





37 



105 



2184 
266 

35 



23 



208 



Superfamily Acroloxacea 

Acroloxidae (note 38) 3 

Superfamily Lymnaeacea 
(note 38) 

Lancidae 3 

Lymnaeidae 34 

Superfamily Ancylacea 
(note 38) 

Ancylidae 13 

Planorbidae 86 

Physidae 6 

11 . Order Stylommatophora (note 39) 
Suborder Orthurethra 

Superfamily Achatinellacea 
(note 40) 

Achatinellidae 23 

Partulidae 12 

Superfamily Cionellacea 
(note 41) 

Amastridae 19 

Cionellidae (Cochli- 

copidae) (note 41) 4 

Superfamily Pupillacea 

Pyramiduli dae 1 

Vertiginidae 39 

Orculidae 5 

Chondrinidae 34 

Pupillidae 28 

Valloniidae 19 

Pleurodiscidae 1 

Enidae 81 

Suborder Mesurethra (note 42) 256 

Superfamily Clausiliacea 238 

Ceriidae (note 42) 5 

*? Filholiidae 1 

Clausiliidae 227 

Megaspiridae 5 

Superfamily Corillacea 8 

Corillidae 8 

Superfamily Strophocheilacea 
Dorcasiidae 3 

Strophocheilidae 7 

Suborder Heterurethra 

Superfamily Succineacea 

Succineidae 26 

Aillyidae (note 43) 1 

Superfamily Athoracophoracea 
Athoracophoridae (note 44) 4 
Suborder Sigm urethra (note 39) 
Infraorder Holopodopes 

Superfamily Achatinacea 

Ferrussaciidae 20 

Subulinidae 80 

Achatinidae 23 

Spiraxidae (note 47) 43 

Superfamily Streptaxacea 

Streptaxidae (note 45) 90 

Superfamily Rhytidacea 
(note 45) 

Acavidae 12 

Haplotrematidae (note 45) 5 
Rhytididae 20 

Chlamydephoridae 1 



10 



31 

27 



1631 
517 
166 



90 



38 



12 



TAYLOR AND SOHL 



Superfamily Bulimulacea 

Bulimulidae 

* ? Anadromidae 

Odontostomidae 

Orthalicidae 

Amphibulimidae (note 43) 

Urocoptidae 
Infraorder Aulacopoda 

Superfamily Endodontacea 

Endodontidae 

Otoconchidae 

Arionidae 

Philomycidae (note 46) 

? Thyrophorellidae 
Superfamily Zonitacea 

Vitrinidae 

Zonitidae 

Parmacellidae 

Milacidae 

Limacidae 

T rigonochlamydidae 

? Systrophiidae (note 45) 
Superfamily Ariophantacea 

Trochomorphidae 

Euconulidae 

Helicarionidae 

Ariophantidae 

Urocyclidae 
Superfamily Testacellacea 

Testacellidae 
Infraorder Holopoda 

Superfamily Polygyracea 

(note 47) 

? Thysanophoridae 

? Ammonitellidae 

Polygyridae 
Superfamily Oleacinacea 

Oleacinidae (note 47) 

Sagdidae (note 47) 
Superfamily Helicacea 

Oreohelicidae (note 47) 

Camaenidae (note 47) 

Bradybaenidae 

Helminthoglyptidae 

Helicidae 

12. Order Sacoglossa (note 48) 

Superfamily Oxynoacea 

Arthessidae (note 31) 

Oxjrnoidae 
Superfamily Elysiacea 

Elysiidae 

Caliphyllidae 

Limapontiidae 

Stiligeridae 

Oleidae 
Superfamily Juliacea 

Juliidae 

13. Order Anaspidea 

Superfamily Aplysiacea 
Akeratidae (note 29) 
Aplysiidae 

14. Order Gymnosomata (note 49) 

Laginiopsidae 
Anopsiidae 



223 



94 

9 

16 

17 

8 

79 



107 

1 

25 

3 

1 

14 

94 

5 

4 

26 



610 
137 



165 



Pneumodermatidae 4 

Cliopsidae 1 

Notobranchaeidae 3 

Clionidae 4 

Thliptodontidae 2 
15. Order Notaspidea (note 50) 

Superfamily Umbraculacea 

Umbraculidae 6 

Superfamily Pleurobranchacea 



Pleurobranchidae 
16. Order Nudibranchia (note 51) 
Suborder Doridoidea (note 52) 
Infraorder Gnathodoridoidea 

Bathydorididae 

Doridoxidae 
Infraorder Cryptobranchia 

Hexabranchidae 

Chrom odor ididae 

Dorididae 

Halgerdidae 



12 



52 



18 
6 



12 



213 
104 

2 



7 




Infraorder Phanerobranchia 




42 


15 




Superfamily (Nonsuctoria) 




22 




305 


Notodorididae 


3 




24 




Polyceridae 


12 




94 




Triophidae 


4 




70 




Gymnodorididae 


3 




73 




Superfamily (Suctoria) 




20 


44 




Onchidorididae 


10 






3 


Goniodorididae 


7 




3 




Corambidae 


2 






504 


Vayssiereidae 
Infraorder Porostomata 


1 


7 




49 


Dendrodorididae 


2 




10 




Phyllidiidae 


5 




5 




Suborder Rhodopoidea 




1 


34 




Rhodopidae 


1 






35 


Suborder Dendronotoidea (note 53) 


29 


13 




Tritoniidae 


10 




22 




Aranucidae 


1 






420 


Lomanotidae 


1 




2 




Scyllaeidae 


3 




94 




Hancockiidae 


1 




80 




Dendronotidae 


1 




51 




Bornellidae 


2 




193 




Fimbriidae 


3 






34 


Dotonidae 


5 






7 


Phylliroidae 


2 




2 




Suborder Arminoidea (note 54) 




17 


5 




Infraorder Euarminoidea 




7 




22 


Heterodorididae 


1 




6 




Arminidae 


5 




3 




Doridoididae 


1 




2 




Infraorder Pachygnatha 




5 


10 




Antiopellidae 


2 




1 




Madrellidae 


2 






5 


Dironidae 


1 




5 




Infraorder Leptognatha 




5 




17 


Gonieolididae 


1 






17 


Heroidae 


1 




1 




Charcotiidae 


3 




16 




Suborder Eolidoidea (note 55) 




62 




17 


Infraorder Pleuroprocta 




? 


1 




Notaeolidiidae 


1 




2 




Coryphellidae 


? 





OUTLINE OF GASTROPOD CLASSIFICATION 



13 



Infraorder Acleioprocta 




? 


Eubranchidae 


? 




Pseudovermidae 


1 




Cuthonidae 


14 




Flabellinidae 


? 




Fionidae 


1 




Calmidae 


1 




Infraorder Cleioprocta 




30 


Facelinidae 


11 




Favorinidae 


10 




Aeolidiidae 


7 




Glaucidae 


2 




Incertae sedis 




1 


? Myrrhinidae 


1 




. Order Soleolifera (note 56) 




27 


Superfamily Onchidiacea 




6 


Onchidiidae 


6 




Superfamily Veronicellacea 




21 


Veronicellidae 


16 




Rathouisiidae 


5 





NOTES 

1 . Numbers of genera of many fami- 
lies and supeffamilies have been taken 
directly from Knight and others (1960). 
Thus several genera unallocated to family 
have been included in the total number of 
genera per superfamily. Archaeogastro- 
poda genera inquirenda (Knight and others, 
1960) have not been counted. The counts 
not taken from Knight and others are ori- 
ginal; we found the numbers given by 
Schilder (1947) are wrong in some cases. 

2. Sohl (1961, p. 50) has established 
the family Weeksiidae for three genera 
formerly included in the Euomphalidae. 

3 . The Cyclostrematidae of Knight and 
others (1960) are a composite group. 
Cyclostrema Marryat, 1818, probably be- 
longs to the Turbinidae Liotiinae (Abbott, 
1950). The next available family name, 
Skeneidae (Wenz, 1938-44), is therefore 
applied to Knight's group. Some of Wenz' s 
Skeneidae and Cyclostrematidae have been 
transferred to the Vitrinellidae (see note 

11). 

4 . Family rank for the Phasianellidae 
as well as the integrity of the group has 
been questioned by Robertson (1958, p. 
250-251). Robertson implied that the two 
subfamilies might be better grouped in 
the Turbinidae. Marcus and Marcus (1960, 
p. 192) have suggested that separate fam- 



ily rank for both phasianellid subfamilies 
may perhaps be warranted. 

5. The Grangerellidae, originally de- 
scribed as pulmonates, are included in 
the Neritacea near theHelicinidae follow- 
ing Zilch (1959-60). Progrange re lia Rus- 
sell, 1941, omitted by Zilch, has been 
added also. 

6. The scope of the Cyclophoracea 
has been changed from that of Wenz (1938- 
44) to that of Tielecke's (1940) ''Cyclo- 
phorinaceae" . Thus the Viviparidae and 
Ampullariidae have been excluded, and we 
group them in a separate superfamily 
Viviparacea. This classification is more 
conservative than that of Volkova, Pche- 
lintsev, and Korobkov (in Pchelintsev and 
Korobkov, 1960), who recognized sepa- 
rate superfamilies for both the Vivipari- 
dae and Ampullariidae. 

The families of Cyclophoracea are those 
of Tielecke (1940). The numbers of ge- 
nera in these families are those of Wenz' s 
subfamilies, distributed according to Tie- 
lecke's classification. The seven genera 
and subgenera of Wenz' s Hainesiinae, 
Ferussininae, and Craspedopominae have 
not been allocated to a family. Carboni- 
spira Yen, 1949, has been included in the 
Cyclophoracea following Knight and others 
(1960). These eight genera of uncertain 
position have been included in the count 
of the superfamily. Maturipupa Pilsbry, 
1927, and Anthracopiipa Whitfield, 1881, 
although placed in the Cylophoracea also 
by Knight and others, are listed here in 
the Ellobiidae following Zilch (1959-60). 

7. The Syrnolopsidae have been trans- 
ferred from the Rissoacea to the Cerithi- 
acea after Mandahl-Barth (1954). In- 
stead of including the group in the Thiari- 
dae as did Mandahl-Barth, we have fol- 
lowed Leloup (1953) in ranking it as a 
family, next to the Thiaridae. 

8. Wenz' s classification of the Hydro- 
biidae has been modified by transferring 
the Ekadantinae to the Assimineidae (see 
Zilch, 1959-60, p. 827). 

9. The name Bulimidae used by Wenz 
has been changed to Bithyniidae in ac- 
cord with Opinion 475 of the International 
Commission on Zoological Nomenclature. 



14 



TAYLOR AND SOHL 



9A. Fretter and Graham (1962, p. 622, 
642) advocated separation of Barleeia 
Clark, 1855, in an independent family. 
It is not certain whether they would in- 
clude all of the Rissoidae Barleeinae of 
Wenz's classification. 

10. The name Acmeidae used by Wenz 
has been changed to Aciculidae in accord 
with Opinion 344 of the International Com- 
mission on Zoological Nomenclature. 

11. Vitrinellidae has been used as the 
name for this family more often than 
either Adeorbidae or Tornidae. The scope 
of the family is that of Pilsbry and Olsson 
(1945, 1952) and Pilsbry (1953). Many 
of the genera were included erroneously 
by Wenz in the archaeogastropods as Ske- 
neidae and Cyclostrematidae. The num- 
ber of vitrinellid genera is based on 
Wenz's Tornidae, on some of his Skenei- 
dae and Cyclostrematidae that are not in- 
cluded in Knight and others (1960), and 
on new genera described by Pilsbry and 
Olsson. 

Genera of Wenz's Skeneidae listed here 
as Vitrinellidae are Calceolata Iredale, 
1918; Caporbis Bartsch, 1915, Callom- 
phala A. Adams and Angas, 1864; Didia- 
nema Woodring, 1928; Idioraphe Pilsbry, 
1922; Leucodiscus Cossmann, 1918; Leu- 
corhynchia Crosse, 1867; Megatyloma 
Cossmann, 1Ъ^Ъ,Р seiidorotella P.Fischer, 
1857; Rostellorbis Cossmann, 1888; So- 
lariorbis Conrad, 1865; Starkeyna Iredale, 
1930; and Teinostoma H. and A. Adams, 
1853. Genera from Wenz's Cyclostre- 
matidae listed here as Vitrinellidae are 
Cithna A. Adams, 1863; Eladio rbi s Ire- 
dale, 1915; and Sczss/Zaöra Bartsch, 1907. 
Macromphalina Cossmann, 1888, was list- 
ed erroneously by Wenz as a synonym of 
Megalomphahis Brusina, 1871, in the Fos- 
saridae. It is included in the Vitrinellidae 
after Pilsbry and Olsson (1952). To these 
we have further added eighteen genera 
and subgenera from the papers by Pils- 
bry and Olsson (1945, 1952) and Pilsbry 
(1953). 

12. Fretter (1948) and Fretter and 
Graham (1954) have pointed out similari- 
ties of Omalogyra Jeffreys, 1860, and 
Rissoella Gray, 1847, to the Pyramidelli- 



dae (Euthyneura) . 

The Skeneopsidae, Omalogyridae, Ris- 
soellidae and Cingulopsidae were listed 
as Rissoacea incertae sedis by Fretter 
and Graham (1962, p. 622-624, 639-640, 
642) . They show some euthyneuran char- 
acters and perhaps even their ordinal po- 
sition will be changed. 

13. Fretter and Patil (1958) estab- 
lished the family Cingulopsidae for their 
new genus Cingulopsis. 

14. Pchelintsev (in Pchelintsev and 
Korobkov, 1960) has established a super- 
family Pseudomelaniacea which we ac- 
cept with minor modifications. Meeko- 
spira Ulrich and Scofield, 1897 (including 
Cambodgia Mansuy, 1914) and Girtyspira 
Knight, 1936, of Pchelintsev's Pseudo- 
melaniidae are included in the Meekospi- 
ridae of the superfamily Subulitacea fol- 
lowing Knight and others (1960). Traja- 
nella Popovici-Hatzeg, 1899, and Paosia 
Bbhm, 1894, which form Pchelintsev's 
Trajanellidae, have been retained in the 
Pseudomelaniidae as in Wenz (1938-44). 
We accept the Glauconiidae of Pchelintsev 
without modification. Thus the following 
genera of Wenz' s classification are brought 
together: Pseiuloglauconia H. Douville' 
1921, from the Cerithiidae; Glaucoma 
Giebel, 1852 {inclnáingG y mneyitome Coss- 
man, 1909), from the Thiaridae (see also 
note 17); and Pseiuiomesalia H. Douville' 
1917, from the Vermetidae (see also note 
16). 

15 . The relationships between Archi- 
tectonicidae and Mathildidae have been 
pointed out by Thiele (1928), who empha- 
sized the heterostrophic protoconch and 
common features of the radula. These 
families were both classed by Thiele 
among the Cerithiacea. Ovechkin and 
Pchelinstev (in Pchelintsev and Korobkov, 
1960) established a superfamily Solari- 
acea for the Solariidae (^ Architectoni- 
cidae). Modifying the name of this super- 
family to Architectonicacea, we also ten- 
tatively add the Omalaxidae, after Wenz. 

The classification of the Mathildidae in 
the Cerithiacea is based entirely upon 
the information provided by Thiele (1928). 
The family is similar to some Archi- 



OUTLINE OF GASTROPOD CLASSIFICATION 



15 



tectonicidae in operculum, radula, and 
heterostrophic protoconch. Risbec (1955, 
p. 70) has observed that the Architectoni- 
cidae have more in common with the eu- 
thyneuran Pyramidellidae than the Ceri- 
thiacea. Both Mathildidae and Archi- 
tectonicidaemay prove to be primitive 
shelled Euthyneura. 

16. Wenz (1938-44) listed 27 genera 
and subgenera of Vermetidae. This as- 
semblage is now recognized as compo- 
site. We follow Keen (1961) in listing 
ten genera and subgenera for the family. 

The seventeen other genera of Wenz' s 
Vermetidae are transferred elsewhere 
(Morton, 1951, 1953,- Keen, 1961). Aga- 
thirses Montfort, 1808; Anguillospira 
Cossmann, 1912; Casimiria Cossmann, 
1899; Laxispira Gabb, 1877; Lilax Fin- 
lay, 1927; Pro vermicular га Kittl, 1899; 
Pseudobrochidium Grupe, 1907; Pyxipoma 
Mörch, 18Q0;Siphomum J. E. Gray, 1850; 
Stephopoma Mörch, 1860; Tenagodus Guet- 
tard, 1770; and Vermiciilaria Lamark, 
1799, are transferred to theTurritellidae. 
But, considering Siphoniiim a synonym of 
Vermiciilaria after Keen (1961), we in- 
crease Wenz' s Turritellidae by eleven 
genera only. Four of Wenz' s vermetids 
are probably or surely annelids instead 
of mollusks: Segmentella, Spiroglyphus , 
Burtinella, and Cryptobia. Serpulorbis 
Sassi, 1827, is a valid vermetid genus, 
but was listed by Wenz as a synonym of 
Lemintina Risso, 1826, which is based on 
an annelid. Pseudomesalia Douville", 1917, 
is transferred to the Glauconiidae follow- 
ing Pchelintsev (in Pchelintsev andKorob- 
kov, 1960). Dihelice Schmidt, 1906, is un- 
recognizable and has not been counted in 
any family. 

17. The Thiaridae of Wenz (1938-44) 
have been diminished by transferring 
Glaucoma Giebel, 1852, and Gymnentome 
Cossmann, 1909, to the Glauconiidae 
(Pseudomelaniacea) after Pchelintsev (in 
Pchelintsev and Korobkov, 1960). The 
rest of the Thiaridae and Wenz' s Lavi- 
geriidae (Cyclophoracea) and Anaplocami- 
dae (Calyptraeacea) have been rearranged 
by Morrison (1954) into the three families 
Thiaridae, Pleuroceridae, and Melanopsi- 



dae on the basis of reproductive charac- 
ters. In the present state of knowledge, 
it is not practicable to distribute all the 
genera listed by Wenz into these three 
families. Therefore, only the total num- 
ber of genera in the three families is 
given. 

18. Risbec (1955, p. 68-69) advocated 
removal of the Triphoridae from the Ce- 
rithiacea. "One ought to make a special 
group intermediate, from certain points 
of view, between the Stenoglossa and the 
Mesogastropoda, -- a group closer, in 
my opinion, to the Columbellidae than to 
the Cerithiidae." [ Translated from the 
original French] . A separate superfamily 
for the Triphoridae is probably justified, 
but we have not established one because 
of uncertainties about where to place it. 

19. Seguenzia Jeffreys, 1876, has been 
classified in two ways. Verrill (1884) 
created a separate family in what are 
now called the Mesogastropoda on the 
basis of the taenioglossate radula. Wood- 
ring (1928) followed Verrill. Thiele (1925) 
transferred the genus to the Trochidae 
in the Archaeogastropoda and this alloca- 
tion has been maintained by Thiele (1929- 
35), Wenz (1938-44), and Knight and others 
(1960). We maintain the Seguenziidae in 
the Mesogastropoda because no anatomi- 
cal data have become available since Ver- 
rill' s work, because the shell features do 
not agree well with other Trochidae, and 
because we wish to call attention to the 
dearth of information about this group. 
We have placed the Seguenziidae in the 
Cerithiacea without conviction, and follow 
Woodring (1928) in listing it after the 
Triphoridae. Most recently Clarke (1961) 
has maintained the Seguenziidae as a sep- 
arate family, placing them doubtfully next 
to the Trochidae in the Archaeogastropoda. 

19A. The names Scalacea and Scalidae 
used by Wenz (1938-44) are not based 
upon a valid generic name. Clench and 
Turner (1951, p. 251) have discussed the 
reasons why Epitonium Roding, 1798, is 
the oldest name for the genus. Epito- 
niidae and Epitoniacea are thus prefer- 
able names for the family and super- 
family. 



16 



TAYLOR AND SOHL 



The family Stenacmidae, included in 
the Amphibolacea by Zilch (1959-60), is 
based upon an epitoniid according to Ro- 
bertson and Oyama (1958). 

20. Melanellacea and Melanellidae have 
been rejected in favor of Eulimacea and 
Eulimidae on the basis of Winckworth's 
(1934, p. 12) arguments. The Entocon- 
chidae and Enteroxenidae have been re- 
moved from this superfamily to an order 
Parasita within the Euthyneura after Ti- 
kasingh and Pratt (1961). 

21. Amplocamus Dall, 1895, formed 
Wenz's family Anaplocamidae in the Ca- 
lyptraeacea. This genus is included in 
the Pleuroceridae (Cerithiacea) after 
Morrison (1954). 

22. The Xenophoridae have been trans- 
ferred from the Strombacea to the Calyp- 
traeacea following Morton (1958a). 

22A. The Eratoidae are classed in the 
Lamellariacea instead of Cypraeacea fol- 
lowing Fretter and Graham (1962, p. 626- 
629). 

23. The name Amphiperatidae, used by 
Wenz, is based upon a genus which is no- 
menclatorially invalid under Opinio^ 261 
of the International Commission on Zoo- 
logical Nomenclature. Ovulidae is the 
next most commonly used name. 

24. Oocorythidae, ranked as a separate 
family by Wenz, have been included in 
the Tonnidae following Turner (1948, p. 
181). 

25. The arrangement of the Neogas- 
tropoda is that of Wenz as modified by 
Risbec (1955). The composition of the 
suborders Stenoglossa and Toxoglossa is 
that of Risbec, so that the Mitridae of 
Wenz have been divided. The Mitrinae 
and Cylindrinae made up the restricted 
family Mitridae, which has been trans- 
ferred from the Volutacea in the Steno- 
glossa to the Toxoglossa as a separate 
superfamily. TheVexillinae have been dis- 
sociated and assigned to two different 
stenoglossan superfamilies: Piisia and 
two included subgenera to the Muricidae; 
and the fifteen other Vexillinae to the 
Nassariidae. Risbec's name Terebracea 
is rejected in favor of the older and 
more common term Conacea. 



The Buccinidae of Thiele (1929-1935) 
and Wenz (1938-1944) have been divided 
by Powell (1951) into the three families 
Buccinidae, Neptuneidae, and Buccinulidae. 
In the present state of knowledge it is 
not practicable to distribute the genera 
and subgenera listed by Wenz into these 
three families, so the total number only 
is given. 

26. The name Melongenidae is pre- 
ferable to Galeodidae because Galeodes 
Roding 1798 is a junior homonym (Clench 
and Turner, 1956). 

27. The orders of the Euthyneura are 
mostly from Zilch (1959-60), listed in 
the sequence of numbers assigned to them 
by Boettger (1955, p. 263). The ordinal 
name Anaspidea is used instead of Ap- 
lysiacea, and the Notaspidea are ranked 
as a separate order, following Odhner 
(1939). 

28. The term Entomotaeniata was pro- 
posed by Cossmann (1896, p. 5) as a sub- 
order to include the Nerineidae and re- 
latives (the mesogastropod Nerineacea of 
later authors). Subsequently Cossmann 
(1921, p. 209-210) concluded that the Py- 
ramidellidae were descended from the ex- 
tinct Nerineacea, although he did not for- 
mally include the Pyramidellidae in the 
Entomotaeniata. Cossmann's summary is 
so incisive that we quote it: 

"The origin of the Pyramidellidae 
seems evident to me: the Cretaceous 
System includes some Ne пиеа- like shells 
{Itieria and especially Itriivia) of which 
the columellar plication and heterostro- 
phic protoconch have the greatest analogy 
with those of Pyramidella. Furthermore, 
it seems incontestable that the posterior 
notch of the lip in the Entomotaeniata, 
exaggerated to the point where it gener- 
ates a subsutural band (Essais V, livr. 
II), could have become reduced in the 
first pyramidellids to a very weak sinus 
or even to a simply protractive outline 
of the posterior part of the outer lip, ex- 
actly as in the opisthobranchs which also 
have the protoconch heterostrophic. Con- 
sequently the Pyramidellidae are descend- 
ed from the latter by way of the Ento- 
motaeniata. But, while the opisthobranchs 



OUTLINE OF GASTROPOD CLASSIFICATION 



17 



have persisted to the present with their 
primitive and very ancient characters, 
their indirect heirs the Pyramidellidae 
are today very distinct in their anatomi- 
cal features, and they resemble each 
other only by their protoconch and by 
the protractive outline of their lip." 
[Translated from the original French with 
changes to conform with the conventional 
orientation of shells] . 

This inferred phylogeny was doubted 
byWenz (1938-1944, p. 64), who thought 
the Nerineacea and Pyramidellidae more 
probably had an earlier, common ances- 
tor. Wenz went on to add: 

''One might query, whether the Neri- 
neacea should not be recognized as a 
strongly aberrant side branch of the opis- 
thobranchs, and the Pyramidellacea also 
brought into closer systematic relation- 
ship with them than is usual. Only in- 
creasing anatomical investigation of the 
pyramidellid genera and of the families 
thought to be related can provide a de- 
cision." [Translated from the original 
German]. 

An affinity between Pyramidellidae and 
Nerineacea has been inferred by many 
paleontologists, for example d'Orbigny 
(1842-1843, p. 73) and Stoliczka (1867- 
1868, p. 172). Cossmann's appreciation 
of the significance of the heterostrophic 
protoconch reflects keen insight. Now 
that the Pyramidellidae have been recog- 
nized as Euthyneura the inclusion of other 
many-whorled high- spired shells in the 
subclass seems less anomalous than pre- 
viously. We approve the grouping of 
Pyramidellacea and Nerineacea in one 
order . Reviving Cossmann' s Entomotaeni- 
ata also obviates proposing a new ordinal 
name for the Pyramidellacea as was sug- 
gested by Morton (1958, p. 177). 

Within the Nerineacea the classification 
has been modified slightly from that of 
Wenz. The Nerinellidae of Pchelintsev 
(in Pchelintsev and Korobkov, 1960) have 
been accepted without modification. The 
family includes 7 genera from Wenz' s 
Nerineidae. 

The Pyramidellacea are composed of 
Pyramidellidae and Streptacididae after 



Knight and others (1960). The Pyrami- 
dellidae are transferred from the Meso- 
gastropoda to the Euthyneura following 
Fretter and Graham (1949). 

29. The scope of the Cephalaspidea is 
that of Odhner (1939) and Thiele (1929- 
1935) except that the Akeratidae are in- 
cluded in the Anaspidea after Boettger 
(1955). The Cephalaspidea of Zilch (1959- 
1960) are the Cephalaspidea, Acochlidioi- 
dea, and Philinoglossoidea of this classi- 
fication. 

Odhner (1939) grouped the families of 
Cephalaspidea into suborders on the basis 
of two characters: degree of development 
of shell, and presence or absence of 
parapodia. Neither Boettger nor Zilch 
used formal categories between family 
and order, but we are establishing super- 
families based on Boettger' s inferred 
lineages. Boettger's hypothetical lines of 
descent were derived largely from degree 
of development of six characters: (1) de- 
gree of detorsión of the visceral connec- 
tives, (2) shortening of the visceral con- 
nectives, (3) change in mutual relationship 
of individual ganglia and their possible 
fusion, (4) position of the pharyngeal nerve 
ring before or behind the pharynx, (5) 
loss of shell, and (6) loss of operculum. 

30. The Acteonellinae of Zilch (1959- 
60) are ranked as a family after Pche- 
lintsev (in Pchelintsev and Korobkov, 
1960). In this group we include Cylin- 
dritella White, 1887, and Peruviella 01s- 
son, 1944, after Zilch, but v.e exclude 
Troostella Wade, 1926, after Pchelintsev. 

31 . Following Evans (1950) and Morton 
(1958b) we remove Volvatella Pease, 1860, 
гпаАгШе s sa Ev2ins, 1950, from theDiaph- 
anidae in the Cephalaspidea and group them 
as a family Arthessidae in theSacoglossa. 

32. Marcus and Marcus (1956) have 
established the family Cylindrobullidae 
for Cylindrobulla Fischer, 1857. The 
genus shows a mixture of primitive and 
specialized characters, but seems most 
probably a primitive Cephalaspidean with 
affinities to the sacoglossan Arthessidae. 
The Cylindrobullidae do not fit readily into 
any other group of Cephalaspidea and 
we have segregated them as a superfamily 



18 



TAYLOR AND SOHL 



Cylindrobullacea. 

33. Ordinal rank for Acochlidiidae and 
relatives is after Odhner (1938, 1939, 
1952) and Marcus (1953). Rank of the 
families and numbers of their genera are 
after Odhner (1952) and Marcus (1953). 
Odhner's name Acochlidiacea is changed 
to Acochlidioidea because we prefer to re- 
strict the ending -acea to superfamilies. 

34. Ordinal rank for the Philinoglos- 
idae is after Odhner (1952) and Marcus 
1953). The number of genera is after 
Marcus (1953). The name Philinoglos- 
sacea is changed to Philinoglossoidea be- 
cause we prefer to restrict the ending 
-acea to superfamilies. 

35. The superfamilies of Basomma- 
tophora are those of Zilch (1959-60) with 
an additional one (unnamed) for the La- 
tiidae and Chilinidae, which Morton (1955) 
suggested should be dissociated from the 
Lymnaeacea (see also note 37). 

36. Pseiidorhytidopilus Cox, 1960 
(Knight and others, 1960, p. 237) has been 
included in the SLphonariidae with simi- 
lar forms placed there by Zilch (1959- 
60). 

36A. The family Stenacmidae, included 
in the Amphibolacea by Zilch (1959-60) is 
based upon an Epitoniid (Mesogastropoda) 
according to Robertson and Oyama(1958). 

37. The Payettiidae were established 
by Dall (1924) as a subfamily Payettinae 
for Payettia Dall, 1924. The subfamily 
was listed under the Planorbidae, but per- 
haps inadvertently. Henderson (1935, p. 
267) recorded that Dall "wrote that he 
had intended to place them in the Ancy- 
lidae, but that probably Payettia and Latia 
really belong together in a separate 
group.". The ranking of Payettia as a 
synonym of Amphigyra Pilsbry, 1906, by 
Zilch (1959-60) was probably based on 
the works by Wenz (1923, p. 1704) and 
Hannibal (1912). Yen (1944) considered 
the genus as one of the Ancylidae. The 
Payettiidae may be most closely related 
to the Latiidae (listed here under an un- 
named superfamily), or possible to Wal- 
ker's (1923) Ancylastruminae (included 
in the Ancylidae of the Ancylacea). Part- 
ly for convenience, and partly to call at- 



tention to the uncertain affinities of the 
group, Dall' s Payettinae are ranked as a 
family and grouped in the same super- 
family as the Latiidae. 

38. The scope of the Lymnaeacea of 
Zilch (1959-60) has been reduced by sep- 
arating off two superfamilies, the Ancy- 
lacea and Acroloxacea, mainly on the ba- - 
sis of the classification of Baker (1956) ■ 
and the work of Bondesen (1950). The 
numbers of genera are practically all from 
Zilch. The distinction between Ancylacea 
and Lymnaeacea was first made by Baker 
(1956) who distinguished the superfamilies 
"Ancyloidea" and "Lymnoidea". Baker's 
names have been modified to conform to 
the customary superfamily endings in mol- ■ 
lusks. The unique features of the Aero- ■ 
loxidae have been recognized previously, 
although the basic differences were not 
expressed by ranking them formally as a 
superfamily. 

The present groupings reflect more 
clearly the relationships of the various 
limpet-like freshwater snails to the forms ■ 
with coiled shells. The patelliform groups ■ 
that were originally united in the com- 
posite family "Ancylidae" have gradu- 
ally been recognized to fall under four 
separate families: the restricted Ancy- 
lidae, Acroloxidae, Lancidae and Latiidae 
(note 37) in different superfamilies. 

The patelliform Acroloxidae (equiva- 
lent to the Ancylinae of Walker, 1923) 
form a distinct family according to Bon- 
desen (1950), who emphasized that they 
have little in common with other Ancyli- 
dae in the broad sense. Not only are 
they less similar to the Planorbidae in 
their internal organization than are the 
restricted Ancylidae (see below), but 
they are not closely related to other 
Basommatophora. "As regards the other 
European patelliform freshwater snail, 
the dextrorse Acroloxus laciistris (L.), 
a study of its egg capsules leaves the 
direct impression that we are here con- 
cerned with a species with an isolated 
position in the system. The highly de- 
viating structure of its capsule with the 
slightly irregular eggs, apparently ar- 



OUTLINE OF GASTROPOD CLASSIFICATION 



19 



ranged without any regular order, and 
the entire absence of any sign of curv- 
ing or spiral torsion makes the capsule 
of this species the most remarkable 
among the capsules of the freshwater 
pulmonates." (Bondesen, 1950, p. 111- 
112). Differences in spermatogenesis 
also "would tend to further separate 
Acroloxus from other Basommatophora" 
(Burch, 1961, p. 16). Hubendick (1962) 
has supported the separate family status 
of the Acroloxidae and inferred from the 
structure of the genitalia that they are 
most closely related to the Latiidae. The 
distinctive features pointed out by these 
authors are here formally recognized by 
grouping the Acroloxidae in a separate 
superfamily. 

Separate family rank for the patelli- 
form Lancidae, instead of subfamily sta- 
tus within the Lymnaeidae, is adopted 
following Baker (1925b). Only three valid 
genera or subgenera are recognized. 
Zalophancylus Hannibal, 1912, was based 
upon the external mold of a fossil fish 
vertebra (Hanna, 1925). 

The number of genera of Lymnaeidae 
is that of Zilch's (1959-60) Lymnaeinae. 

The Ancylidae as listed here are most 
of Walker's (1923) family, after the re- 
moval of the following groups: the An- 
cylinae Walker (1923) ( = Acroloxinae 
Thiele (1931)), the Protancylinae, Neo- 
planorbinae and Lancinae. These re- 
stricted Ancylidae correspond to the An- 
cylidae, Ferrissiidae, and Rhodacmeidae 
of Zilch (1959-60). 

The scope of the Planorbidae is basi- 
cally that of Zilch, with addition of his 
Neoplanorbidae. Thus from the Ancylidae 
of Walker (1923) both the Neoplanorbinae 
and Protancylinae have been transferred 
to the Planorbidae. The scope of the 
Neoplanorbinae is that of Walker, so that 
two genera (instead of only one as in 
Thiele, 1929-35, v. 1, p. 480) have been 
added to the Planorbidae. Protancylus 
Sarasin, 1898, forming Walker's Protan- 
cylinae, was transferred to the Planor- 
bidae by Pilsbry and Bequaert (1927, p. 
132). 

The Physidae have been accepted as in 
Zilch (1959-60). 



39. Subdivision of the Stylommato- 
phora into four suborders, and of the 
Sigmurethra into three infraorders, is 
after Baker (1955, 1962). The family 
groupings by Zilch (1959-60) have been 
maintained except where distributed in 
different superfamilies by Baker. 

40. The Achatinellacea may possibly 
be an unnatural group. Baker (1956) 
suggested that the Partulidae may belong 
either near the Ceriidae (in theClausi- 
liacea of the Mesurethra), or near the 
Pupillacea in the Orthurethra. The Acha- 
tinellidae he included in the Pupillacea. 

Cooke and Kondo (1960) have concluded 
that the Achatinellidae and Tornatellinidae 
are most reasonably grouped as one fam- 
ily Achatinellidae. 

41. Recognition of a superfamily Cio- 
nellacea for the Cionellidae and Amas- 
tridae ows Baker (1956). Cochlicopa 
Ferussac, 1821, is not a senior syno- 
nym of Cionella Jeffreys, 1829, or even 
a member of the same family (Kennard, 
1942, Pilsbry, 1948, p. 1047). The name 
Cionellidae, used by Pilsbry, is there- 
fore substituted for Zilch's Cochlicopidae. 

42. Baker (1961) ranked the Ceriidae 
and Clausiliidae as separate families 
within the same superfamily of the Me- 
surethra. The Filholiidae are placed in 
the Clausiliacea with a query after Zilch 
(1959-60). The Megaspiridae are included 
after Baker (1961). The Acavidae of Zilch 
have been divided by Baker (1955, 1962) 
into Dorcasiidae and Strophocheilidae in 
the Mesurethra, and Acavidae in the Holo- 
podopes in the Sigmurethra. The high- 
spired, many-whorled shells of Ceriidae, 
Clausiliidae, and Megaspiridae have been 
retained in the superfamily Clausiliacea 
which has much the same scope as that 
of Zilch. Corillacea and Strophocheilacea 
have been added as coordinate categories 
with the Clausiliacea. 

The name Cerionidae has been emended 
to Ceriidae following Baker (1957). 

43. Aillya Odhner, 1927, has been re- 
moved from the sigmurethran Amphibuli- 
midae and segregated as the heterure- 
thran family Aillyidae after Baker (1955). 

44. The number of genera of Athora- 
cophoridae is from Solem (1959, p. 44). 



20 



TAYLOR AND SOHL 



45. The Systrophiidae have been in- 
cluded with a query in the Zonitacea, fol- 
lowing Baker (1956), instead of in a su- 
perfamily with the Rhytididae and Haplo- 
trematidae as classified by Zilch (1959- 
60). Polygyratia Gray, 1847, is included 
in the Systrophiidae after Baker (1925a) 
rather than in the Camaenidae as Zilch 
(1959-60) grouped it. 

Baker (1956) transferred the three gen- 
era of Austroselenitinae from the Haplo- 
trematidae to the Streptaxidae with doubt. 

46. The number of genera of Philomy- 
cidae is from Solem (1959, p. 77). 

47. Baker (1956,1962) has divided the 
Oleacinidae of previous classifications 
into two families. The restricted Olea- 
cinidae are included in theholopod super- 
family Oleacinacea. The Spiraxidae, with 
subfamilies Spiraxinae, Streptostylinae 
and Euglandininae, are included in the in- 
fraorder Holopodopes and superfamily 
Achatinacea. Counts of genera are based 
on Zilch (1959-60) as follows: Oleacinidae 
are Zilch's " Varicelleae" and Oleacina 
R'dding, 1798, in the strict sense. Spirax- 
idae are Zilch's Spiraxinae, " Euglan- 
dineae", and " Streptostyleae", except for 
Oleacina. 

The Ammonitellidae were classified 
as a subfamily of the Camaenidae by 
Zilch (1959-60). They were considered 
a distinct family by Wurtz (1955), and 
thought by Baker (1956) to belong either 
in the Polygyracea or Endodontacea. 

Baker (1956) ranked the Thysanophor- 
idae as a family of either Polygyracea 
or Endodontacea. The group was included 
in the Polygyridae with doubt by Zilch 
(1959-60). 

The Sagdidae have been transferred 
from the Polygyracea to Oleacinacea after 
Baker (1956). Gouostouiopsis Pilsbry, 
1889, was thought to belong to the Sagdi- 
dae rather than Camaenidae by Wurtz 
(1955). 

The Oreohelicidae are ranked as a fam- 
ily, instead of a subfamily of Camaen- 
idae, after Wurtz (1955). Solaropsis 
Beck, 1837, is not one of the restricted 
Camaenidae according to Wurtz (1955), 
but is nevertheless counted in this fami- 



ly because it cannot be placed readily 
anywhere else. Torrechrysias Moreno, 
1936, was treated as a synonym of Chry- 
sias Pilsbry, 1929, by Zilch (1959-60) 
but is considered valid following Wurtz 
(1955). 

48. The subdivision of the Sacoglossa 
and the ranks of these subdivisions are 
from Kawaguti and Baba (1959). Their 
name Tamanovalvidae is rejected because, 
according to Keen and Smith (1961) and 
Baba (1961), Tamanovalva Kawaguti and 
Baba, 1959, is invalid and because the 
older name Juliidae is available. Julia 
Gould, 1862, is known to be a sacoglossan 
(Morrison, 1961) and hence we accept 
Thiele's (1929-35) family Juliidae for this 
group. The number of genera in the fam- 
ily is from Keen and Smith (1961). We 
here also replace Tamanovalvacea Kawa- 
guti and Baba, 1959, byJuliacea. Berthe- 
liniidae Baba, 1961, is a much younger 
name than Juliidae. In this classification 
only the one family Juliidae is recognized 
within its superfamily, and hence the name 
Bertheliniacea Baba, 1961, is invalid. 

49. The number of genera of Gymno- 
somata is from Thiele (1929-35). 

50. The division of the Notaspidea into 
Umbraculacea and Pleurobranchacea is 
that of Odhner (1939). 

51. Thiele's (1929-35) classification 
of the Nudibranchia is much out of date, 
but there is no comprehensive revision 
of the group available. The outline gi- 
ven here is an attempt to fit Thiele's 
groups into the framework established by 
Odhner (1934, 1936, 1939, 1941). 

Odhner (1939) and following him Boett- 
ger (1955) have divided the nudibranchs 
into four suborders. To these four, we 
add a fifth one for the aberrant genus 
Rhodope, following Thiele (1929-35), Hoff- 
man (1932-39, p. 193), and Marcus and 
Marcus (1952). The endings of the names 
have been changed to reserve -acea for 
superfamily rank only. 

Thompson (1961) has recognized two 
types of larval shells in the Nudibranchia 
and pointed out their significance for 
classification. Most of the known spe- 
cies have type 1 (spiral) which occurs 



OUTLINE OF GASTROPOD CLASSIFICATION 



21 



also in the orders Notaspidea and Saco- 
glossa. In the suborders Dendronotoidea 
and Eolidoidea both type 1 and type 2 
(egg-shaped) are present. In the classi- 
fication outlined herein, the two types 
never occur within the same family, and 
within the Eolidoidea they do not occur 
within even the same infraorder. 

52. Odhner (1934) made a twofold pri- 
mary subdivision of the doridoids, into 
Gnathodoridacea and Eudoridacea, the 
latter being divided again into Crypto- 
branchia and Phanerobranchia. Marcus 
(1957, 1961) has added Bergh's old group 
Porostomata as a third primary subdi- 
vision. To preserve the family group- 
ings of present classification without in- 
troducing more than one category between 
suborder and superfamily, we introduce 
a fourfold division of the suborder into 
the infraorders Gnathodoridoidea, Crypto- 
branchia, Phanerobranchia, and Poro- 
stomata. 

The Gnathodoridoidea include two fami- 
lies, monotypic as in Thiele' s classifi- 
cation. 

The Cryptobranchia include the doridids 
and close relatives. Dorididae are split 
into many families by Pruvot-Fol (1954), 
but following Odhner (1934) only Chromo- 
dorididae, Dorididae, andHalgerdidae are 
recognized. These three include all of 
Thiele' s (1929-35) Dorididae except for 
the Dendrodoridinae. The Hexabranchi- 
dae are monotypic, as in Thiele. 

The Phanerobranchia are accepted in 
the sense of Odhner (1941), who divided 
them into Suctoria and Nonsuctoria. If 
these groups are ranked as superfamilies 
they should have names based on a typi- 
cal genus, but for present purposes no 
new formal names are necessary and 
Odhner' s terms are listed in parentheses. 
The four families of Nonsuctoria are 
those of Odhner (1941); they form part 
of Thiele' s Polyceridae. The Onchidori- 
didae and Goniodorididae of the Suctoria 
make up the rest of Thiele' s Polyceridae. 
The Corambidae and Vayssiereidae have 
been accepted in the sense of Thiele. 

Two families have been segregated in 
the Porostomata by Pruvot-Fol (1954) 



and Marcus (1957). These are the Dori- 
didae, Dendrodoridinae and Phyllidiidae 
of Thiele. 

53. Odhner' s classification (1936) of 
the Dendronotoidea has been accepted 
with only minor changes. Tritoniidae 
has been substituted for Duvauceliidae, 
and Tritonia Cuvier, 1803, has been con- 
sidered distinct from Duvaucelia Risso, 
1826, following Odhner (1939). The works 
of Odhner (1936) and Thiele (1929-35) 
have been combined in counting the gen- 
era of Tritoniidae. 

54. The threefold division of the Ar- 
minoidea is that of Odhner (1939). In 
the Euarminoidea, Odhner' s three fami- 
lies Heterodorididae, Arminidae, and 
Doridoididae are equivalent to Thiele' s 
Arminidae and Doridoididae. In the Pa- 
chygnatha, the families are those of both 
Odhner and Thiele except that the name 
Antiopellidae is used following Odhner in 
place of Thiele' s Zephyrinidae. The com- 
position of the Leptognatha is after Odh- 
ner (1939). Goniaeolididae is changed 
in conformity with the original spelling 
of GonieoUs Sars, 1859. This family 
and also Heroidae are used as in Thiele' s 
classification. The Charcotiidae are ac- 
cepted in the sense of Odhner (1934), so 
that Charcotia Vayssiere, 1906, and Pseu- 
dotritonia Thiele, 1912, are removed from 
Thiele' s Notaeolidiidae. Telarma Odhner, 
1934, is the third genus of this family. 

55. Division of the Eolidoidea into 
three groups is from Odhner (1934, 1939). 
The Pleuroprocta include two families. 
The Notaeolidiidae as restricted by Odh- 
ner (1934) include only one genus. The 
second pleuroproct family of Odhner 
(1939), Coryphellidae, is included in 
Thiele' s Flabellinidae. 

The Acleioprocta of Odhner (1939) are 
made up of three families, Eubranchidae, 
Cuthonidae, and Calmidae. Three addi- 
tional families, Fionidae, Flabellinidae, 
and Pseudovermidae are recognized by 
Marcus and Marcus (1955), Marcus (1961), 
and Pruvot-Fol (1954). These six fami- 
lies include the Tergipedidae, Fionidae, 
Calmidae, Pseudovermidae, and most of 
the Flabellinidae of Thiele' s classification. 



22 



TAYLOR AND SOHL 



The cleioproct Eolidoidea are classed 
by Odhner (1934, 1939) in four families, 
which are equivalent to Thiele' s Aeo- 
lidiidae. The four families recognized 
here are those which Marcus (1955, 1957, 
1958) has modified from Odhner's classi- 
fication. Ranking and numbers of genera 
of Facelinidae and Favorinidae are after 
Marcus (1958). Odhner's Aeolidiidae and 
Spurillidae are combined after Marcus 
(1955, 1957) into the Aeolidiidae whose 
number of generals counted from Thiele' s 
Aeolidiinae. Glaucinae of Thiele are 
ranked as a family after Odhner. 

Thirty-one genera of the Coryphellidae, 
Eubranchidae, and Flabellinidae have not 
been allocated to a specific family, but 
have been included in the count of genera 
within the Eolidoidea. 

The monotypic Myrrhinidae of Thiele' s 
classification have been listed as Eoli- 
doidea incertae sedis. 

56. Soleolifera was used by Thiele 
for the Rathouisiidae and Veronicellidae 
only, but we follow Zilch in applying this 
name to the order. For Soleolifera in 
Thiele' s sense we substitute Veronicel- 
lacea. The numbers of genera of Onchi- 
diidae are from Solem (1959, p. 37) and 
of Rathouisiidae and Veronicellidae from 
Thiele (1929-35). 



ACKNOWLEDGMENTS 

The manuscript has been read by S. 
Stillman Berry, Redlands, California; John 
B. Burch, Museum of Zoology, University 
of Michigan; A. Myra Keen, Department 
of Geology, Stanford University; Harald A. 
Rehder, U. S. National Museum; Robert 
Robertson, Academy of Natural Sciences, 
Philadelphia; and Wendell P. Woodring, 
и. S. Geological Survey. They do not 
necessarily agree with all details of rank- 
ing and nomenclature. 



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ROBERTSON, Robert and Katura OYAMA,1958, 
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RUSSELL, L. S,, 1941, Progrange relia, a new 
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SOHL, N. F., 1961, Archeogastropoda, Meso- 
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matischen Weichtierkunde. Gustav Fischer, 
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OUTLINE OF GASTROPOD CLASSIFICATION 



25 



, 1938-1944, Gastropoda, Teil 1, 

Allgemeiner Teil und Prosobranchia. In : 
Schindewolf, Handbuch der Paläozoologie, 
V. 6. Borntraeger, Berlin, vii + 1639 p. 

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Mollusca - II. J. Conchol., 20: 9-15. 

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discussion of results. Carnegie Inst, Wash- 
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WURTZ, C. В., 1955, The American Camaenidae 
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Sei. Philadelphia, 107: 99-143, pl. 1-19. 

YEN, Teng-Chien, 1944, Notes on fresh-water 
mollusks of Idaho formation at Hammett, 
Idaho. J. Paleont., 18: 101-108. 

ZILCH, Adolf, 1959-60, Gastropoda, Teil 2, 
Euthyneura, In: Schindewolf, Handbuch der 
Paläozoologie, v. 6, Borntraeger, Berlin, 
xii + 834 p. 



ZUS AMME NF ASSUNG 



UMRISS EINER KLASSIFIKATION DER GASTROPODEN 



Die Systematik grösserer Abschnitte der Юasse Gastropoda ist in verschiedenen 
neueren Veröffentlichungen zusammenfassend behandelt worden. Lebende und fossile 
Archäogastropoden und andere paläozoische Gastropoden werden von Knight u. a. 
(1960) erfasst, Zilch (1959-60) behandelt umfassend die lebenden sowie fossilen 
schalentragenden euthyneuren Schnecken, während Wenz (1938-44) als jüngste um- 
fassende Quelle für lebende und fossile post-paläozoische Meso- und Neogastropoden 
anzusehen ist. 

Unser Umriss einer Einteilung der Gastropoden wurde zwar hauptsächlich aus 
den obigen Quellen aufgestellt, wurde jedoch, insbesondere für die schalenlosen 
Gruppen, auch aus anderen Arbeiten ergänzt, wie in den Anmerkungen angegeben. 
Dieser Umriss* reicht nicht unter Familienrang herab. Nur wenige von anderen als 
unseren Hauptquellen vorgeschlagenen Familien oder Superfamilien wurden darin 
aufgenommen. Ebenfalls herangezogene neuere und allgemein zusammenfassende 
Arbeiten sind die von Korobkov (1955) Ptschelintsev und Korobkov (1960) (angeführt 
unter Pchelintsev) und Termier und Termier (1952). In einigen Fällen, besonders 
was die Neogastropoden anbelangt, bestehen ziemlich allgemein Meinungsverschie- 
denheiten über die von Wenz aufgestellten Familien. Wir haben mangels einer jün- 
geren monographischen Bearbeitung, trotzdem seine Einteilungbeibehalten, haben 
jedoch die alternativen gebräuchlichen Benennungen in Klammern hinzugefügt. 
Erklärungen darüber wie die verschiedenartigen Enteilungen in Einklang gebracht 
wurden sind in den Anmerkungen zu finden. 

Die Zahl der Gattungen und Untergattungen in der Gastropoden (7 ,324) stammt 
mit nur wenigen Abänderungen aus obigen Arbeiten und ist wann immer möglich 
für jede der Familien angegeben (linke Spalte der "Classification"). Später be- 
schriebene Gattungen wurden nur selten aufgenommen (wie angemerkt). Unsere 
Einteilung ist daher zu verschiedenen Graden veraltet und enthält viele der Schwä- 
chen der angeführten zusammenfassenden Werke. 

Die Gastropoden sind hier in die 2 Unterklassen Streptoneura und Euthyneura 
eingeteilt, wobei, nach Boettger (1955) und Zilch (1959-60), die altbekannten Opistho- 
branchia und Pulmonata durch Spengels Euthyneura ersetzt werden, während die 
Benennung Streptoneura, wegen der parallellen Ableitung des Wortes, den Namen 
Prosobranchia vorzugsweise ersetzt. Obwohl die Streptoneura (4,218 Gattungen und 
Untergattungen) die grössere der beiden Gruppen darstellen, sind sie in bloss 3 
Gruppen eingeteilt, während die Euthyneura (3,106 Gattungen und Untergattungen) 
grössere Verschiedenheiten des Aufbaues aufweisen und in 14 Ordnungen zerfallen. 
Die Grössenverhältnisse dieser Ordnungen, nach der Zahl ihrer Gattungen und 
Untergattungen berechnet, sind in Abbildungen 1 und 2 dargestellt, wobei die erstere 
unserer eigenen, sowohl lebende als auch fossile Formen enthaltenden Юassifikation 
entspricht, und die letztere derjenigen von Thiele (1929-35), welche nur lebende 
Formen umfasst. Der einzige markante Unterschied zwischen den beiden Darstel- 
lungen besteht darin, dass in der letzteren die Stylommatophora, hauptsächlich auf 
Kosten der Archeogastropoda, umfangreicher sind. 



*Die Sternchen bezeichnen durchwegs fossile Gruppen. 



26 TAYLOR AND SOHL 

Im allgemeinen scheinen innerhalb der Gastropoden, mit Ausnahme der Ordnung 
Archäogastropoda, die Einschnitte in Familien und Superfamilien ungefähr gleich- 
wertigen morphologischen Unterschieden zu entsprechen. Die genannte Ordnung 
zeigt eine feinere Einteilung, indem viele Familien und Unterfamilien verhältnis- 
mässig wenige Gattungen enthalten. 



RÉSUMÉ 
e'bAUCHE D'UNE CLASSIFICATION DES GASTÉROPODES 

La Classification des principaux groupes de la classe des gastéropodes se 
trouve résumée dans plusieures publications plus ou moins récentes. Ainsi Knight 
et autres (1960) couvrent les archéogastéropodes vivants et fossiles ainsi que les 
autres groupes paléozoiques. Récemment, Zilch (1959-60) traite des mollusques 
euthyneures pourvus de coquilles, vivants et fossiles, tandis que l'oeuvre de Wenz 
(1938-44) représente la plus récente source comprehensive pour les méso- et néo- 
gastéropodes post-paléozoiques vivants et fossiles. 

Notre classification gastéropode a été esquissée principalement d'après ces 
sources, mais elle a aussi été supplémentée par d'autres travaux, surtout en ce 
qui concerne les groupes atestes, comme indiqué dans les notes. Cette classiñ- 
cation* ne descend qu'au niveau familial. Familles et sous-familles proposées par 
d'autres auteurs que ceux déjà cités ne sont inclus que dans une faible mesure. Les 
principaux travaux additionnels récents et généraux pris en considération sont ceux 
de Korobkov (1955), de Ptchélintsev et Korobkov (1960) (voir Pchélintsev) et de 
Termier et Termier (1952). Dans certains cas, spécialement en ce qui concerne 
les néogastéropodes, il y a désagrément assez uniforme au sujet de la classification 
familiale de Wenz. Nous avons pourtant retenu sa classiñcation faute de traité 
monographique plus récent, ajoutant toutefois, entre parenthèses, les désignations 
alternatives courantes. De quelle manière les classification divergentes ont été 
réconciliées est expliqué dans les notes. 

Le nombre de genres et sous-genres gastéropodes (7,324) est derivé princi- 
palement des sources indiquées ci-haut est et donné pour chaque famille (colonne 
gauche, classification) dans la mesure du possible. Les genres décrits après la 
publication de ces travaux ne sont que rarement inclus. Notre classification est 
donc périmée à dégre variable et participe des faiblesses de ces ouvrages généraux. 

Les gastéropodes sont ici divisés en 2 sous-classes, les streptoneures et les 
euthyneures, ces derniers étant formés par la fusion des opisthobranches et des 
pulmones, selon Boettger (1955) et Zilch (1959-60), tandis qu'en vertu de sa déri- 
vation similaire, le terme streptoneure remplace celui de prosobranche. Quoique 
les streptoneures (4,218 genres et sous-genres) forment le plus grand de ces 2 
groupes, ils ne sont divisés qu'en 3 ordres, pendant que les euthyneures (3,106 
genres et sous-genres), de plus grande diversification structurelle, sont divisés en 
14 ordres. Les dimensions relatives de ces ordres, selon le nombre de leurs 
genres et sous-genres, sont illustrées par les figures 1 et 2, dont la première se 
base sur la présente classification comprenant groupes vivants et fossiles et la 
seconde sur celle de Thiele (1929-35) ne comprenant que formes vivantes. La seule 
différence frappante entre ces deux illustrations est, dans la seconde, l'accrois- 
sement des stylommatophores au dépens des archéogastéropodes. 

Les coupures familales et sur- familiales dans les gastéropodes semblent cor- 
respondre à peu près au même degré de differentiation morphologique, à l'exception 
de l'ordre des archéogastéropodes qui a été plus finement divisé et dont les familles 
et surfamilles n'ont que relativement peu de genres. 



*Les groupes pourvxu d'un astérisque sont uniquement fossiles. 



OUTLINE OF GASTROPOD CLASSIFICATION 27 

RESEÑA 
UNA RESEÑA DE LA CLASIFICACIÓN DE LOS GASTRÓPODOS 

Varias publicaciones recientes han resumido la clasificación de gran parte de 
la clase Gastropoda. Knight y otros han estudiado los arqueogastrópodos fósiles y 
vivientes, así como otros gastrópodos paleozoicos. Zilch (1959-1960) ha estudiado 
los fósiles y vivientes con concha de la subclase Euthyneura. La fuente de información 
más reciente acerca de mesogastrópodos y neogastrópodos fósiles y vivientes es 
Wenz (1938-1944). 

Hemos llevado a cabo una reseña de la clasificación de los gastrópodos basada 
principalmente en esta información, suplementándola con información especial para 
los grupos con o sin conchilla como indicamos en nuestras notas. Esta clasiñcación* 
se extiende únicamente a la familia. Nos hemos mostrado conservadores en lo que 
se refiere al reconocimiento de familias y superfamilias propuestas en otras fuentes 
de información distintas a las que han servido para estos trabajos básicos. También 
hemos considerado otros trabajos generales llevados a cabo recientemente por Korob- 
kov (1955), Pchelintsev y Korobkov (1960)y Termiery Termier (1952). La forma en 
que estas clasiñcaciones divergentes han sido reconciliadas se explica en nuestras 
notas. 

En algunos casos, especialmente entre los neogastrópodos, existe una discre- 
pancia uniforme en lo que se refiere a la clasificación por familias de Wenz. Debido 
a que no existe ningún tratamiento monográfico reciente para estos grupos, nos 
hemos limitado a retener la clasificación de Wenz, dando entre paréntesis una lista 
de alternativas comunes. 

Damos una lista (columna izquierda en la clasificación) del número de géneros y 
subgéneros de los gastrópodos (7 ,324) siempre que nos es posible. Estas figuras han 
sido tomadas de las fuentes de información mencionadas anteriormente con las 
modificaciones indicadas. Los géneros descritos después de la publicación de estos 
estudios se incluyen muy raremente, por lo tanto nuestra clasificación está en cierto 
modo atrasada incluyendo muchos de los puntos débiles de los trabajos generales ya 
mencionados. 

En este trabajo, los gastrópodos se dividen en 2 sub-clases, Streptoneura y 
Euthyneura, siendo la ultima mencionada formada por los opistobranquios y pul- 
monados, dejando el término Steptoneura para los prosobranquios, debido a la deri- 
vación similar del nombre. A pesar de que los Streptoneura constituyen el grupo 
más grande (4,218 géneros y subgéneros) se dividen únicamente en 3 órdenes, mien- 
tras que los Euthyneura (3,106 ge'neros y subgéneros), que son más diversos en su 
estructura, se dividen en 14 órdenes. La medida relativa de estos órdenes, basadas 
en el mismo número de géneros y subgéneros, se muestra en las figuras 1 y 2. 
Nuestra clasificación, incluyendo fósiles y vivientes, constituyen la base de la figura 
1. La clasificación de Thiele (1929-1935) incluyendo únicamente las formas vi- 
vientes, constituyen la base de la figura 2. La única diferencia entre los dos cuadros 
es el hecho de que en la figura 2, los Stylommatophorahan aumentado principalmente 
a expensas de los arqueogastrópodos. 

En general creemos que las incisiones familiares y superfamiliares a través 
de los gastrópodos, corresponden en el mismo grado a la diferencia morfológica, 
con la excepción de que los arqueogastrópodos se han dividido más finamente que 
otras órdenes, resultando así que muchas de las familias y superfamilias tienen 
relativamente muy pocos géneros. 



*Taxa marcada con un asterisco se refiere iónicamente a los fósiles. 



28 TAYLOR AND SOHL 



ОЧЕРК СИСТЕМАТИКИ БРШОНОП'К 

Д. В. Тэйлор и Н. Ф. Сол 
Управление Геологии США, Вашингтон, Д. К. 

Настоящий очерк является компиляцией классификации се- 
мейств и сверхсемейств, взятых главным образом из трудов: 
"Handbuch der Paläozool cgie" (Wenz und Zilch) и из 
"Tr-estise on Inverteorate Faleontolcgy" (Knlght and others) 
К этим двуи системам сделаны добавления, главным образом в 
области безраковинных групп, чтобы создать более полную 
классификацию, насколько это возможно. Некоторые роды и 
подроды приведены для каждого семейства, но роды, описанные 
после появления в печати упомянутых выше трудов, включены 
неполностью. Таким образом относительная величина групп 
указана только в общих чертах. В примечаниях имеются ссыл- 
ки для наиболее важных групп систематики с объяснениями, 
каким образом были согласованы бывшие расхождения в их 
классификации . 

Брюхоногие (7324 рода и подрода) разделены на два 

подкласса: Streptoneura и Euthiyneura. Хотя str-eptone- 
ura (4218 родов и подродов) подкласс более численный, 

он разделен только на три отряда. Но huthyneura (3106 

родов и подродов) подкласс более разнообразный по строеншо 

своему и поэтому он разделен на 14 отрядов. 



OUTLINE OF GASTROPOD CLASSIFICATION 



29 



INDEX OF SCIENTIFIC NAMES 



Abyssochrysidae, 10 
Acavidae, 11,19 
Achatinacea, 11,20 
Achatinidae, 11 
Achatinellacea, 11,19 
Achatinellidae, 11,19 
Aciculidae, 1,14 
Acleioprocta, 13,21 
Aclididae, 10 
Acmaeidae, 9 
Acmeidae, 14 
Acochlidiacea, 18 
Acochlidiidae, 11,18 
Acochlidioidea, 8,11,17,18 
Acroloxacea, 11,18 
Acroloxidae, 11,18,19 
Acroloxinae, 19 
Acroloxus, 18,19 
Acroreidae, 11 
Acteonacea, 11 
Acteonellidae, 11 
Acteonellinae, 17 
Acteonidae, 11 
Adeorbidae, 9,14 
Aeolidiidae, 13,21,22 
Aeolidiinae, 22 
Agathirses, 15 
Aglajidae, 11 
Aillya, 19 
Aillyidae, 11,19 
Akeratidae, 12,17 
Amaltheidae, 10 
Amastridae, 11,19 
Amberleyacea, 9 
Amberleyidae, 9 
Ammonitellidae, 12,20 
Amphibolacea, 11,15,18 
Amphibolidae, 11 
Amphibulimidae, 12,19 
Amphigyra, 18 
Amphiperatidae, 10,16 
AmpuUariidae, 9,13 
Anadromidae, 12 
Anaplocamidae, 15,16 
Anaplocamus, 16 
Anaspidea, 8,12,16,17 
Ancylacea, 11,18 
Ancylastrmninae, 18 
Ancylidae, 11,18,19 
Ancylinae, 19 
Anguillospira, 15 
Anomphalacea, 9 
Anomphalidae, 9 
Anopsiidae, 12 
Anthracopupa, 13 
Antiopellidae, 12,21 
Aplysiacea, 12,16 
Aplysiidae, 12 



Aporrhaidae, 10 
Aranucidae, 12 
Archaeogastropoda, 7,8,13,15 
Architectonic acea, 10,14 
Architectonicidae, 10,14,15 
Arionidae, 12 
Ariophantacea, 12 
Ariophantidae, 12 
Arminidae, 12,21 
Arminoidea, 12,21 
Arthessa, 17 
Arthessidae, 12,17 
Assimineidae, 9,13 
Asterophilidae, 10 
Ataphridae, 9 
Athoracophoracea, 11 
Athoracophoridae, 11,19 
Atlantacea, 10 
Atlantidae, 100 
Atyidae, 11 
Aulacopoda, 12 
Austroselenitinae, 20 
Barleeia, 14 
Barleeinae, 14 
Basommatophora, 11,18,19 
Bathydorididae, 12 
Bellerophontacea, 8 
Bellerophontidae, 8 
Bertheliniacea, 20 
Bertheliniidae, 20 
Bithyniidae, 9,13 
Bornellidae, 12 
Brachytremidae, 10 
Bradybaenidae, 12 
Buccinacea, 10 
Buccinidae, 10,16 
Buccinulidae, 10,16 
Bulimidae, 9,13 
Bulimulacea, 12 
Bulimulidae, 12 
Bullacea, 11 
BuUidae, 11 
Bursidae, 10 
Burtinella, 15 
Caecidae, 10 
Calceolata, 14 
Caliphyllidae, 12 
Callomphala, 14 
Calmidae, 13,21 
Calyptraeacea, 10,15,16 
Calyptraeidae, 10 
Camaenidae, 12,20 
Cambodgia, 14 
Cancellariidae, 10 
Caporbis, 14 
Capulidae, 10 
Carbonispira, 13 
Carinariidae, 10 



Casimiria, 15 
Cassididae, 10 
Catantostomatidae, 9 
Cavolinidae, 11 
Cephalaspidea, 7,11,17 
Ceriidae, 11,19 
Cerionidae, 19 
Ceritellidae, 11 
Cerithiacea, 10,13,14,15,16 
Cerithiidae, 10,14,15 
Cerithiopsidae, 10 
Charcotia, 21 
Charcotiidae, 12,21 
Chilinidae, 11,18 
Chlamydephoridae, 11 
Chondrinidae, 11 
Chondropomidae, 9 
Choristidae, 9 
Chrom odorididae, 12,21 
Chrysias, 20 
Cingulopsidae, 9,14 
Cirtgulopsis , 14 
done lia, 19 
Cionellacea, 11,19 
Cionellidae, 11,19 
Cirridae, 9 
Cithna, 14 
Clausiliacea, 11,19 
Clausiliidae, 11,19 
Cleioprocta, 13 
Clionidae, 12 
Cliopsidae, 12 
Clisospiracea, 9 
Clisospiridae, 9 
Cocculinacea, 9 
Cocculinidae, 9 
Cochlicopa, 19 
Cochlicopidae, 11,19 
Cochostomatidae, 9 
Codonochilidae, 9 
Coelostylinidae, 10 
Colombellinidae, 10 
Columbellidae, 10,15 
Conacea, 10,16 
Conidae, 10 
Coralliophilidae, 10 
Corambidae, 12,21 
Coreospiridae, 8 
Corillacea, 11,19 
Corillidae, 11 
Coryphellidae, 12,21,22 
Craspedopominae, 13 
Craspedostomatacea, 9 
Craspedostomatidae, 9 
Crossostomatidae, 9 
Cryptobia, 15 
Cryptobranchia, 12,21 
Ctenosculidae, 10 



30 



TAYLOR AND SOHL 



Cuthonidae, 13,21 
Cyclophoracea, 9,13,15 
Cyclophoridae, 9 
Cyclostrema, 13 
Cyclostrematidae, 13,14 
Cylindrinae, 16 
Cylindritella, 17 
Cylindrobulla, 17 
CylindrobuUacea, 11,18 
Cylindrobullidae, 11,17 
Cymatiidae, 10 
Cymbuliidae, 11 
Cypraeacea, 10,16 
Cypraeidae, 10 
Cyrtolitidae, 8 
Dawsonellidae, 9 
Deianiridae, 9 
Dendrodorididae, 12,21 
Dendrodoridinae, 21 
Dendronotidae, 12 
Dendronotoidea, 12,21 
Desmopteridae, 11 
Diaphanacea, 11 
Diaphanidae, 11,17 
Diastomidae, 10 
Didianema, 14 
Dihelice, 15 
Dironidae, 12 
Dorcasiidae, 11,19 
Dorididae, 12,21 
Doridoidea, 12,21 
Doridoididae, 12,21 
Doridoxidae, 12 
Dotonidae, 12 
Duvaucelia, 21 
Duvauceliidae, 21 
Ekadantinae, 13 
Elachorbis , 14 
Elasmonematidae, 9 
EUobiacea, 11 
Ellobiidae, 11,13 
Elysiacea, 12 
Elysüdae, 12 
Endodontacea, 12,20 
Endodontidae, 12 
Enidae, 11 

Enteroxenidae, 11,16 
Entoconchidae, 11,16 
Entomotaeniata, 8,10,16,17 
Eolidoidea, 12,21,22 
Eotomariidae, 8 
Epitoniacea, 10,15 
Epitoniidae, 10,15 
Epitonimn, 15 
Eratoidae, 10,16 
Euarminoidea, 21 
Eubranchidae, 13,21,22 
Euconulidae, 12 
Eudoridacea, 21 
Euglandininae, 20 
Eulimacea, 10,16 
Eulimidae, 10,16 
Euomphalacea, 8 



Euomphalidae, 8,13 
Euomphalopteridae, 9 
ETiStomidae, 10 

Euthyneura, 7,8,10,14,15,16,17 
Facelinidae, 13,22 
Fasciolariidae, 10 
Favorinidae, 13,22 
Ferrissiidae, 19 
Ferrussaciidae, 11 
Ferussininae, 13 
Ficidae, 10 
Filholiidae, 11,19 
Fimbriidae, 12 
Fionidae, 13,21 
Fissurellacea, 9 
Fissurellidae, 9 
Flabellinidae, 13,21,22 
Fossaridae, 10,14 
Fusinidae, 10 
Galeodes, 16 
Galeodidae, 10,16 
Gastropteridae, 11 
Girtyspira, 14 
Glaucidae, 13 
Glaucinae, 22 
Glauconia, 14,15 
Glauconiidae, 10,14,15 
Gnathodoridacea, 21 
Gnathodoridoidea, 12,21 
Goniaeolididae, 21 
Gonieolididae, 12 
Gonieolis, 21 
Goniodorididae, 12,21 
Gonostomopsis, 12 
Gosseletinidae, 8 
Grangerellidae, 9,13 
Gymnentome, 14,15 
Gymnosomata, 8,12,20 
Gymnodorididae, 12 
Hainesiinae, 13 
Halgerdidae, 12,21 
Haliotidae, 9 
Hancockiidae, 12 
Haplotrematidae, 11,20 
Harpidae, 10 
Hedylopsidae, 11 
Helcionellacea, 8 
Helcionellidae, 8 
Helicacea, 12 
Helicidae, 12 
Helicarionidae, 12 
Helicinidae, 9,13 
Helicotomidae, 8 
Helminthoglyptidae, 12 
Heroidae, 12,21 
Heterodorididae, 12,21 
Heterurethra, 11 
Hexabranchidae, 12,21 
Hipponicacea, 10 
Hipponicidae, 10 
Holopeidae, 9 
Holopoda, 12 
Holopodopes, 11,19,20 



Hydatinidae, 11 
Hydrobiidae, 9,13 
Hydrocenidae, 9 
Hydrococcidae, 9 
Idioraphe, 14 
Iravadiidae, 9 
Itieria, 16 
Itieriidae, 11 
Itruvia, 16 
Janthinidae, 10 
Julia, 20 
Juliacea, 12,20 
Juliidae, 12,20 
Kittlidiscidae, 9 
Lacunidae, 9 
Lagini ops idae, 12 
Lamellariacea, 10,16 
Lamellariidae, 10 
Lancidae, 11,18,19 
Lancinae, 19 
Latia, 18 

Latüdae, 11,18,19 
Laubellidae, 9 
Lavige riidae, 15 
Laxispira, 15 
Lemintina, 15 
Lepetellidae, 9 
Lepetidae, 9 
Leptognatha, 21 
Leucodiscus, 14 
Leucorhynchia, 14 
Lilax, 15 
Limacidae, 12 
Limapontiidae, 12 
Liotiinae, 13 
Littorinacea, 9 
Littorinidae, 9 
Lomanotidae, 12 
Lophospiridae, 8 
Loxonematacea, 10 
Loxonematidae, 10 
Luciellidae, 8 
Lymnaeacea, 11,18 
Lymnaeidae, 11,19 
Lymnaeinae, 19 
Macluritacea, 8 
Macluritidae, 8 
Macro »iphalina, 14 
Madrellidae, 12 
Magilidae, 10 
Maizaniidae, 9 
Marginellidae, 10 
Mathildidae, 10,14,15 
Maturipupa, 13 
Meekospira, 14 
Meekospiridae, 10,14 
Megalo»iphalus, 14 
Megaspiridae, 11,18,19 
Megatyloma, 14 
Melanellacea, 10,16 
Melanellidae, 10,16 
Melaniidae, 10 
Melanopsidae, 10,15 



OUTLINE OF GASTROPOD CLASSIFICATION 



31 



Melongenidae, 10,16 
Mesogastropoda, 9,15,17,18 
Mesurethra, 11,19 
Metoptomatidae, 9 
Microdomatacea, 9 
Microdom atidae, 9 
Microhedylidae, 11 
Micromelaniidae, 9 
Milacidae, 12 
Mitracea, 10 
Mitridae, 10,16 
Mitrinae, 16 
Modulidae, 10 
Murchisoniacea, 9 
Murchisoniidae, 9 
Muricacea, 10 
Muricidae, 10,16 
Myrrhinidae, 13,22 
Naricidae, 10 
Nassariidae, 10,16 
Nassidae, 10 
Naticacea, 10 
Naticidae, 10 
Neogastropoda, 7,10,16 
Neoplanorbidae, 19 
Neoplanorbinae, 19 
Neptuneidae, 10,16 
Nerinea, 16 
Nerineacea, 11,16,17 
Nerineidae, 11,17 
Nerinellidae, 11,17 
Neritacea, 9,13 
Neritidae, 9 
Neritopsidae, 9 
Nododelphinulidae, 9 
Nonsuctoria, 12,21 
Notaeolidiidae, 12,21 
Notaspidea, 8,12,16,20,21 
Notobranchaeidae, 12 
Notodiaphanidae, 11 
Notodorididae, 12 
Nudibranchia, 12,20 
Odontostomidae, 12 
Oleacina, 20 
Oleacinacea, 12,20 
Oleacinidae, 12,20 
Oleidae, 12 
Olividae, 10 
Omalaxidae, 10,14 
Omalogyra, 14 
Omalogyridae, 9,14 
Omphalotrochidae, 8 
Onchidiacea, 13 
Onchidiidae, 13,22 
Onchidorididae, 12,21 
Onychochilidae, 8 
Oocorythidae, 16 
Opisthobranchia, 8 
Orbitestellidae, 9 
Orculidae, 11 
Oreohelicldae, 12,20 
Oriostomatacea, 9 
Oriostomatidae, 9 



Orthalicidae, 12 
Orthurethra, 11,19 
Otinidae, 11 
Otoconchidae, 12 
Ovulidae, 10,16 
Oxynoacea, 12 
Oxynoidae, 12 
Pachygnatha, 12,21 
Paedophoropodidae, 10 
Palaeotrochacea, 9 
Palaeotrochidae, 9 
Palaeozygopleuridae, 10 
Paosia, 14 
Parasita, 7,11,16 
Paraturbinidae, 9 
Parmacellidae, 12 
Partulidae, 11,19 
Patellacea, 9 
Patellidae, 9 
Payettia, 18 
Payettiidae, 11,18 
Payettiinae, 18 
Peraclidacea, 11 
Peraclididae, 11 
Peruviella, 17 
Phanerobranchia, 12,21 
Phanerotrematidae, 8 
Phasianellidae, 9,13 
Phenacolepadidae, 9 
Philinacea, 11 
Philinidae, 11 
Philinoglossacea, 18 
Philinoglossidae, 11,18 
Philinoglossoidea, 7,11,17,18 
Philomycidae, 12,20 
Phyllidiidae, 12,21 
Phylliroidae, 12 
Physidae, 11,19 
Phymatopleuridae, 9 
Pilidae, 9 
Plagiothyridae, 9 
Planaxidae, 10 
Planitrochidae, 9 
Planorbidae, 11,18,19 
Platyacridae, 9 
Platyceratacea, 9 
Platyceratidae, 9 
Plethospiridae, 9 
Pleurobranchacea, 12,20 
Pleurobranchidae, 12 
Pleuroceridae, 10,15,16 
Pleurodiscidae, 11 
Pleuroprocta, 12,21 
Pleurotomariacea, 8 
Pleurotomariidae, 9 
Pneumodermatidae, 12 
Polyceridae, 12,21 
Polygyracea, 12,20 
Polygyratia, 20 
Polygyridae, 12,20 
Polytremariidae, 9 
Pomatiasidae, 9 
Porcelliidae, 9 



Porostomata, 12,21 
Portlockiellidae, 9 
Potamididae, 10 
Poteriidae, 9 
Procerithiidae, 10 
Procymbuliidae, 11 
Progrange re lia, 13 
Prosobranchia, 8 
Protancylinae, 19 
Protancylus, 19 
Provermicularia, 15 
Psendobrochidium, 15 
Psetidoglauconia, 14 
Pseudomelaniacea, 10,14,15 
Pseudomelaniidae, 10,14 
Pseiidomesalia, 14,15 
Pseudophoracea, 9 
Pseudophoridae, 9 
Pseudorhytidopilus , 18 
Pseudorotella, 14 
Pseutosacculidae, 10 
Pseiidotritonia, 21 
Pseudovermidae, 13,21 
Pseudozygopleuridae, 10 
Pterotracheidae, 10 
Pulmonata, 8 
Pupillacea, 11,19 
Pupillidae, 11 
Pupinidae, 9 
Purpurinidae, 9 
Pusia, 16, 
Pyramidella, 16 
Pyramidellacea, 11,17 
Pyramidellidae, 11,14,15,16,17 
Pyramidulidae, 11 
Pyrenidae, 10 
Pyxipoma,. 15 
Raphischismatidae, 9 
Raphistomatidae, 8 
Rathouisiidae, 13,22 
Retusidae, 11 
Rhodacmeidae, 19 
Rhodope, 20 
Rhodopidae, 12 
Rhodopoidea, 12 
Rhytidacea, 11 
Rhytididae, 11,20 
Ringiculidae, 11 
Rissoacea, 9,13,14 
Rissoellidae, 9,14 
Rissoidae, 9,14 
Rissoella, 14 
Rostellorbis, 14 
Runcinidae, 11 
Sacoglossa, 8,12,17,20,21 
Sagdidae, 12,20 
Scalacea, 10,15 
Scalidae, 10,15 
Scaphandridae, 11 
Schizogoniidae, 9 
Scissilabra, 14 
Scissurellidae, 9 
Scyllaeidae, 12 



32 



TAYLOR AND SOHL 



Segmentella, 15 
Segnenzia, 15 
Seguenziidae, 10,15 
Serpulorbis, 15 
Sigmurethra, 11,19 
Sinuitidae, 8 
Sinuopeidae, 8 
Siphonariacea, 11 
Siphonariidae, 11,18 
Siphonium, 15 
Skeneidae, 9,13,14 
Skeneopsidae, 9,14 
Solariacea, 14 
Solarüdae, 10,14 
Solariorbis, 14 
Solaropsis, 20 
Soleolifera, 8,13,22 
Spiratellacea, 11 
Spiratellidae, 11 
Spiraxidae, 11,20 
Spraxinae, 20 
Spiroglyphus , 15 
Spirostylidae, 10 
Spurillidae, 22 
Starkeytm, 14 
Stenacmidae, 16,18 
Stenoglossa, 10,15,16 
Stenothyridae, 9 
Stephopoma, 15 
Stiliferidae, 10 
Stiligeridae, 12 
Stomatellidae, 9 
Streptacididae, 11,17 
Streptaxacea, 11 
Streptaxidae, 11,20 
Streptoneura, 7,8 
Streptostylinae, 20 
Strombacea, 10,16 
Strombidae, 10 
Strophocheilacea, 11,19 
Strophocheilidae, 11,19 
Struthiolariidae, 10 
Stylommatophora, 7,11,19 
Subulinidae, 11 
Subulitacea, 10,14 



Subulitidae, 10 
Succineacea, 11 
Succineidae, 11 
Suctoria, 12,21 
Symmetrocapulidae, 9 
Synceratidae, 9 
Syrnolopsidae, 10,13 
Systrophiidae, 12,20 
Татагю valva, 20 
Tamanovalvacea, 20 
Tamanovalvidae, 20 
Teirwstoma, 14 
Telarma, 21 
Temnotropidae, 9 
Tenagodus, 15 
Terebracea, 16 
Terebridae, 10 
Tergipedidae, 21 
Testacellacea, 12 
Testacellidae, 12 
Thaisidae, 10 
Thecosomata, 8,11 
Thiaridae, 10,13,14,15 
Thliptodontidae, 12 
Thyrophorellidae, 12 
Thysanophoridae, 12,20 
Titiscaniidae, 9 
Tonnacea, 10 
Tonnidae, 10,16 
Tornatellinidae, 19 
Tornidae, 9,14 
Torre chry Sias, 20 
Toxoglossa, 10,16 
Tra^ysmidae, 9 
Trajanella, 14 
Trajanellidae, 14 
Trichotropidae, 10 
Trigonochlamydidae, 12 
Trimusculidae, 11 
Triophidae, 12 
Triphoridae, 10,15 
Tritonia, 21 
Tritoniidae, 12,21 
Trochacea, 9 
Trochaclisidae, 9 



Trochidae, 9,15 
Trochomorphidae, 12 
Trochonematacea, 9 
Trochonematidae, 9 
Trochotomidae, 9 
Troostella, 17 
Trimcatellidae, 9 
Tubinidae, 9 
Turbinidae, 9,13 
Turridae, 10 
Turritellidae, 10,15 
Umbraculacea, 12,20 
Umbraculidae, 12 
Unnamed superfamily, 11 
Urocoptidae, 12 
Urocyclidae, 12 
Valloniidae, 11 
Valvatacea, 9 
Valvatidae, 9 
Vanikoridae, 10 
Vasidae, 10 
Vayssiereidae, 12,21 
Velainellidae, 9 
Vermetidae, 10,14,15 
Vermicularia , 15 
Veronicellacea, 13,22 
Veronicellidae, 13,22 
Vertiginidae, 11 
Vexillinae, 16 
Vitrinellidae, 9,13,14 
Vitrinidae, 12 
Viviparacea, 9,13 
Viviparidae, 9,13 
Volutacea, 10,16 
Volutidae, 10 
Volvatella, 17 
Weeksiidae, 8,13 
Xancidae, 10 
Xenophoridae, 10,16 
Z alo pliancy lu s , 19 
Zephyrinidae, 21 
Zonitacea, 12,20 
Zonitidae, 12 
Zygitidae, 9 
Zygopleuridae, 10 



МА1ЛСОЮС1А, 1962, 1(1): 33-53 



А CRITICAL CATALOGUE OF THE NOMINAL GENERA AND SPECIES OF 
NEOTROPICAL PLANORBIDAE 

Harold W. Harry 
Ida, Louisiana, U.S.A. 

ABSTRACT 

The genera of Neotropical Planorbidae have only a few species as far north as 
the southern United States of North America. Of the 11 nominal genera which are 
based on type species of the Neotropics, only 3, Taphius, Drepanotrema and 
Acrorbis, are considered valid. An additional unnamed genus is recognized but 
deliberately left unnamed here. Although the Nearctic genus Helisoma does ex- 
tend as far south as Central America, it is pointed out that the citation of other 
Nearctic and Palearctic genera from the Neotropics lacks confirmation by ana- 
tomical data. Some Neotropical and African planorbid genera may be identical, 
but as the former seem to have priority in all known cases, the question has not 
been pursued. 

An attempt is made to cite the original references and type localities of all 
nominal planorbid species of the Neotropics. Of these, 207 are arranged in 21 
"species groups." The members of each group are probably synonyms. Thirty 
two species are lumped as incertae sedis. Some of these seem to be distinct 
from the 21 species groups, but lack of anatomical data prevents their being 
placed in genera. Eleven nomina mida and 4 extralimital species are listed. 
An extensive bibliography is given. 



In the preparation of anatomical ac- 
counts of the Puerto Rican Planorbidae I 
found it difficult to determine what names, 
both generic and specific, ought to be ap- 
plied to them. The present catalogue was 
therefore compiled as a guide. An alpha- 
betical or chronological arrangement of 
the species and genera seemed of little 
value, owing to the large number of spe- 
cies described, and the many genera with 
which they have been combined. The ar- 
rangement as here presented was chosen 
partly on the basis of anatomical and eco- 
logical studies, tobe presented elsewhere, 
and partly on the basis of studies of the 
collections and libraries of the U.S. Na- 
tional Museum and the Museum of Zoology 
of the University of Michigan. I am in- 
debted to Dr. Harald Rehder and Dr. J.P.E. 
Morrison of the former institution, and 
to Dr. Henry van der Schalle of the lat- 
ter, for their generosity in allowing me 
free access to the important collections 
of which they are custodians. I am also 
grateful to Dr. Lobato Paraense and Dr. 
Walter Biese for providing anatomical 
material of several South American spe- 



cies. Few additions or changes have been 
made in the manuscript since it was put 
aside in the spring of 1958. 

Over two hundred and fifty species of 
planorbid snails were named from the 
Neotropics between 1798 and 1957. Most 
of them were placed in the genus Planor- 
bis, which served during the nineteenth 
century as a general depository for nearly 
every species of the family. Owing chief- 
ly to the works of Pilsbry (1934), F. С 
Baker (1945) and Hubendick (1955), it is 
now apparent that a large number of ge- 
nera may be recognized in the family. 
These genera are based mainly on in- 
ternal anatomy rather than shell charac- 
ters. The genus Planorbis,3.s restricted 
by the workers cited, is now known to 
live only in the Palearctic faunal realm. 
Several other genera have been estab- 
lished for the species of the Neotropics. 
It is becoming increasingly evident that 
there are far fewer biological species of 
Planorbidae in the Neotropics than the 
number of nominal species recorded in 
the literature. 

At the present stage of knowledge there 



(33) 



34 



H. W. HARRY 



can be no general agreement on the de- 
finition of the various genera, or their 
limits (i.e., which species are to be in- 
cluded in each genus). There are also 
likely to be differences of opinion on 
which of the nominal species are to be 
recognized as biologically valid. Pro- 
bably in both instances some arbitrary 
decisions will ultimately have to be made. 
The present catalogue tries merely to 
summarize the nomenclature to date, and 
thus to bring into sharper focus the many 
problems involved, rather than to settle 
them. 

The interpretation of some early de- 
scriptions of species depends on a pro- 
cess of elimination of the biological spe- 
cies known to occur in the area of the 
type locality. There are some type lo- 
calities which are open to doubt (e.g., 
Planorbis glabratus Say: see Pilsbry 
1934). Of the many species described 
from unknown localities (see Dunker 1848), 
only those referred to the Neotropics by 
later authors have been included in the 
present list. 



GEOGRAPHICAL LIMITS 

There is a rather well defined division 
between the Neotropical andNearctic Pla- 
norbidae. The line of separation is ap- 
proximated by the southern boundary of 
the United States. Few species cross it. 
Helisoma, which is predominantly a Ne- 
arctic genus with several species, extends 
into the Antilles and to Central America, 
but its presence in South America is very 
dubious. Drepanotrema and Taphhis are 
predominantly Neotropical genera, each 
with one or two species extending into 
Texas, Louisiana or Florida. In general, 
the species of Neotropical Planorbidae 
are widely distributed within their faunal 
realm. This is in striking contrast to 
the terrestrial gastropods of the same 



area, which usually have very limited 
ranges. A few species are included in 
the following catalogue which have their 
type localities in the United States, either 
because they have been cited from the 
Neotropics, or seem (e.g. Planorbis eii- 
cosmius Bartsch) to belong to Neotropi- 
cal genera. Fossil genera and species 
have not been included. 



CHRONOLOGICAL LIST OF THE 

NOMINAL PLANORBID GENERA 

OF THE NEOTROPICS 

The Bulinidae and Planorbidae are 
sometimes considered as subfamilies of 
the Planorbidae. I prefer to consider 
them as families within the superfamily 
Planorbacea,-"- for reasons to be given 
elsewhere. A catalogue of all nominal 
species of Plesiophysaf which is the only 
known genus of Bulinidae in the New 
World, has been given by Bequaert and 
Clench (1939). 

It is now evident that some Neotropi- 
cal planorbid species, at least in the 
Taphiinae,^are probably congeneric and 
perhaps even conspecific with African 
species. In all cases presently known, 
the Neotropical genera have precedence 
over the nominal African genera (e.g., 
Biomphalaria Preston 1910, Afroplanorbis 
Thiele 1931). Unfortunately, litüe atten- 
tion has been given to the African Pla- 
norbidae other than the Taphiinae, and so 
it is not practical at present to comment 
on the probable relationships of the other 
groups on the two continents. 

The species of Neotropical Planorbidae 
have sometimes been cited in the genera 
Gyraidus, Promenetiis, Anisiis, Segmen- 
tina, Platwrbula, PImwrbis and perhaps 
others. Such combinations with extra- 
limital genera have yet to be substanti- 
ated by anatomical studies. In the fol- 
lowing list names proposed as subgenera 



^This superfamily name is here used for the first time. ED. 

^ Plesiophysa is not usually included in the bulinlds but placed in the separate planorbid sub- 
family Plesiophysinae. ED. 
^This subfamily name is here used for the first time. ED. 



A CATALOGUE OF NEOTROPICAL PLANORBIDAE 



35 



or sections are included as genera, since 
they would have that legal status accord- 
ing to the International Rules of Zoolog- 
ical Nomenclature. Similarly, subspe- 
cific names and varieties are treated as 
species. 

HELISOMA Swainson 1840. Type-spe- 
cies, by original designation, Planorbis 
bicarinatus Sowerby (which is P, anceps 
Menke). A discussion of the taxonomy 
of this genus has been given by F. C. 
Baker (1945). This is the only Nearctic 
genus definitely known, on the basis of 
anatomical data, to extend into the Neo- 
tropics. 

PLANORBINA^ Haldeman 1843. The 
vague description accompanying Halde- 
man' s proposal is obviously open to a 
variety of interpretations, and he cited 
no species in this group. Dall (1905) se- 
lected as type-species Planorbis olivaceus 
"Spix" Wagner (which is Planorbis gla- 
bratiis Say). Pilsbry (1934) insisted that 
P. olivaceus did not comply with the ori- 
ginal description of the genus. No species 
could be attributed to the genus with cer- 
tainty before Dall's arbitrary selection 
of a genotype in 1905. Meanwhile the 
genus Taphius had been made available. 

TAPHIUS^H. and A. Adams 1855 .Type- 
species by monoty^y, Planorbis andecolus 
d'Orbigny. Unless some earlier name is 
discovered, this genus will stand for a 
large number of Neotropical and African 
Planorbid snails. 

DREPANOTREMA Fischer and Crosse 
1880. Type-species by monotypy, Pla- 
norbis ysabelensis Crosse and Fischer 
(which is Planorbis anatinum d'Orbigny) . 

ARMIGERUS 4 dessin 1884. The type- 
species, by designation of Morrison (1947), 
is Planorbis albicans Pfeiffer. H. В. 
Baker (1947) objected to Morrison's re- 
surrection of this overlooked name on 



several grounds. И accepted, Armige rus 
Clessin would have priority over Obstruc- 
tio Haas, but both names seem super- 
fluous, since the type species show few 
or no characters of importance to sepa- 
rate them from Taphius. 

TROPICORBIS Brown and Pilsbry 1914. 
Type-species by original designation, PZa- 
norbis liebmanni Dunker (which is Pla- 
norbis havanensis Pfeiffer). This genus 
is not well differentiated from Taphius, 
and may be superfluous. 

PLATYTAPHIUS Pilsbry 1924. Type- 
species by original designation, PZanoröes 
heteropleurus Pilsbry and Vanatta. The 
anatomy of the genotype shows no major 
differences from Taphius, according to 
the account of Hubendick (1955, 1955a), 
and Haas (1955) found intergrades in shell 
form between this nominal species and 
Taphius andecolus (d'Orbigny). This ge- 
neric concept may be superfluous. 

FOSSULORBIS Pilsbry 1934. Type- 
species by original designation, PZa«or&¿s 
cultratus d'Orbigny (which is Planorbis 
kermatoides d'Orbigny). This generic 
concept may be superfluous. 

AUSTRALORBIS Pilsbry 1934. Type- 
species by original designation, Planorbis 
guadaloupensis Sowerby (which is Pla- 
norbis glabratus Say). Proposed to re- 
place Planorbina "Haldeman" Dall 1905, 
the anatomy shows no characters of ge- 
neric importance to separate it from 
Taphius, and this genus may be super- 
fluous . 

ACRORBIS Odhnerl937. Type-species 
by original designation, Acrorbis Petri- 
cola Odhner. A very distinctive genus 
with only one known species. 

OBSTRUCTIO Haas 1939. Genotype by 
original designation, Planorbis janeirensis 
Clessin (which is probably Planorbis al- 
bicans Pfeiffer). Probably superfluous. 



'*Since much consideration has lately been given to the generic status of the various planorbid 
species acting as vectors of Schistosoma mansoni, attention is drawn to a recent review, dis- 
cussing relationships and priorities, by Barbosa et al. (1961, Ann. Mag. Nat. Hist., Ser. 13, 
4:371-375) and to a request to the International Commission on Zoological Nomenclature by 
Wright (1962, Bull. Zool. Nomencl., pt. 1, 19:39-41) for suppressing the above terms. Note 
further that Walter (1962, Malacologia, 1(1): 115-137) considers Taphius to be generally distinct 
from the group in question. ED. 



36 



H. W. HARRY 



LATEORBIS F. С. Baker 1945. Type- 
speciesby original designation, Planorbis 
palUdus C. B. Adams. Probably super- 
fluous . 

THE NOMINAL SPECIES OF 
NEOTROPICAL PLANORBIDAE 

In the following list, the citation of the 
original description of each nominal spe- 
cies is given. It includes references to 
any figures accompanying that description. 
The type locality is added in parentheses. 
Subsequent references are rarely cited, 
except when they are emendations made 
by the original author. Thus, d'Orbigny 
(1837) redescribed and figured species 
which he had described earlier (1835). 
It is notable that his later descriptions 
differ somewhat from his original ones, 
particularly in the number of whorls gi- 
ven. Dunker redescribed and figured spe- 
cies in the Conchylien-Cabinet which he 
had only described earlier (1848). Many 
of the descriptions are so vague as to 
render identification almost impossible, 
and these will consequently be interfireted 
differently by different authors. The spe- 
cies of Morelet (1849, 1851) are parti- 
cularly difficult to identify. The group- 
ing of trivial names into genera and sub- 
families requires some arbitrary deci- 
sions. These will be necessary until stu- 
dies have been made on the anatomy of 
all nominal species, preferably from their 
type localities. Within each group, the 
nominal species are arranged alphabeti- 
cally. 



HELISOMATINAE 

Genus Helisoma 

Group of Helisoma foveale Menke 

1. AFFINIS C.B. Adams 1849. Planorbis affinis 
C.B. Adams 1849, Contrib. Conch. No. 3, p. 
44. Not figured. (Jamaica). 

2. ANCYLOSTOMUS Crosse and Fischer 1879- 
Planorbis ancylostomus Crosse and Fischer 
1879, Jour, de Conchyl. 27:341. Not figured. 
(Vera Cruz, Mexico). 1880, Misc. Sei. Мех., 
Moll., 2:63, PI. 32, Fig. 5a, 5b. 



3. APPLANATUS von Martens 1899- Planorbis 
tenuis var. applanatus von Martens 1899, Biol. 
Centr. Amer., Moll., p. 384, PI. 21, Fig. 3. 
(Central Mexico, Plateau of Mexico). Not P. 
applanatus Thomae 1854; see P. pertenuis 
F.C. Baker 1940. 

4. AURICULATUS Clessin 1884. Planorbis au- 
riculatus Clessin 1884, Syst. Conch. -Cab. 
Mart, and Chem. Ed. 2, Planorbis, p. 163, 
PI. 24, Fig. 10. (Jamaica, Bluefields). 

5. BELIZENSIS Crosse and Fischer 1879- Plan- 
orbis belizensis Crosse and Fischer 1879, 
Jour, de Conchyl. 27:342. Not figured. (Belize 
(British Honduras)). 1880, Misc. Sei. Мех., 
Moll., 2:68, PI. 32, Fig. 6, 6a, 6b. 

6. BOUCARDl Fischer and Crosse 1880. Planor- 
bis tenuis var. boucardi Fischer and Crosse 
1880, Misc. Sei. Мех., Moll. 2:61, PI. 32, Fig. 
3a-b. (Near Mexico City). 

7. CARIBAEUS d'Orbigny 1841. Planorbis caribae- 
us d'Orbigny 1841, in Sagra's Hist. . .Cuba, 
Moll., 1:193, PI. 13, Figs. 17-19. ("Environs 
de la Havane. . . aussi à la Vera Cruz, au 
Mexique"). 

8. CHAPALENSIS Pilsbry 1920. Planorbis tenuis 
Chapalensis Pilsbry 1920, Proc. Acad. Nat. 
Sei. Phila., p. 192-193, Fig. 1, p. 193. ("Laguna 
de Chápala, State of Jalisco" (Mexico)). 

9. CHIAPASENSIS Fischer and Crosse 1880. 
Planorbis ancylostomus var. chiapasensis 
Fischer and Crosse 1880, Mise. Sei. Мех., 
Moll., 2:63-64, PI. 34, Fig. 5 ("E'tat de 
Chiapas" (Mexico)). 

10. COLON "Clessin" von Martens 1899. Planor- 
bis colon "Clessin" von Martens 1899, Biol. 
Centr. Amer., Moll., p. 399- Error for P. coton 
Clessin 1884, q.v. 

11. CONTRERAS! Pilsbry 1920. Planorbis con- 
trerasi Pilsbry 1920, Proc. Acad. Nat. Sei. 
Phila., p. 193, text Fig. 2. ("Laguna de 
Chápala, State of Jalisco"(Mexico)). 

12. COSTARICENSIS Preston 1907. Planorbis cos- 
taricensis Preston 1907, Ann. and Mag. Nat. 
Hist., 7 Ser., 20:496-497, text Fig. 16. ("Cata- 
lina, Province of Guavacaste, Costa Rica"). 

13. COTON "Morelet" Clessin 1884. Planorbis 
coton "Morelet" Clessin 1884, Syst. Conch. - 
Cab. Mart, and Chem. Ed. 2, Planorbis, p. 209, 
PI. 33, Fig. 3. (Locality unknown). Clessin 
spelled it coton on page 209, in the index and 
in the explanation of the figures. He did not 
correct it in the errata, yet von Martens (1899) 
changed the spelling (to P. colon, q.v.) and 
attributed it to Central America, suggesting it 
is P. carihaeus d'Orbigny. 



A CATALOGUE OF NEOTROPICAL PLANORBIDAE 



37 



14. EQUATORIUS Cousin 1887. Planorbis equa- 
toriiis Cousin 1887, Bull. See. Zool. France, 
12:263-264, PI. 4, Fig. 8. ("Equateur") 
spelled "aequatortus" on the plate. 

15. EUDISCUS Pilsbry 1934. Helisoma duryi 
eudiscus Pilsbry 1934, Proc. Acad. Nat. Sei. 
Phila., 86:42-43, PI- 9, Figs. 4-9- ("Miami 
River above Miami" (Florida)). Has been cited 
by several authors as occurring in the Antilles. 

16. EXAGGERATUS von Martens 1899- Planorbis 
tenuis var. exaggeratus von Martens 1899, 
Biol. Centr. Amer., Moll., p. 385- Not figured. 
("Central Mexico, Lake Patzcuaro"). 

17. FOVEALIS Menke 1830. Planorbis fovealis 

Menke 1830, Synop. Method. Mollusc , p. 37, 

cites "Lister Conch, tab. 140 fig. 47," where 
the word "lam" appears adjacent to the figure. 
This has been interpreted by Pilsbry (1934:45) 
to be Jamaica. 

18. FRAGILIS Dunker 1850. Planorbis fragilis 
Dunker 1850, Syst. Conch. -Cab. Mart, and 
Chem., Ed. 2, Planorbis, p. 46-47, PL 10, 
Fig. 41-43- ("In der Nähe von Mexico mit 
Planorbis lenuis Phil."). 

19. GUATEMALENSIS Clessin 1884. Planorbis 
guatemalensis Clessin 1884, Syst. Conch. - 
Cab. Mart, and Chem., Ed. 2, Planorbis, p. 
209-210, PL 32, Fig. 7. ("Centralamerika, 
Guatemala"). 

20. HUMILIS C.B. Adams 1851- Planorbis humilis 
C.B. Adams 1851. Contrib. Conch. No. 8, p. 
131-132. Not figured. (Jamaica). 

21. INTERMEDIUS "Philippi" Dunker 1850. Plan- 
orbis intermedins "Philippi" Dunker 1850, 
Conch. -Cab. Mart, and Chem. Ed. 2, Planorbis, 
p. 39, as a synonym of P. tumidus Pfeiffer. 
(No locality, evidently Mexico). PL 16, Figs. 
18, 19 (appeared 1844). Clessin, 1884, Ibid., 
p. 196, PL 11, Fig. 1,2 (appeared 1882). (Vera 
Cruz, Mexico). Not P. intermedias T. de Char- 
pentier 1837, N.D. Allg. Schweiz. Gesellsch. 
1, P- 21. 

22. JUVENILIS von Martens 1899. Planorbis tenuis 
var. juvenilis von Martens 1899» Biol. Centr. 
Amer., MolL, p. 384, PL 21, Fig. 4. (Central 
Mexico: ditches near the city of Mexico). 
Proposed as a new name for P. solidus Weig- 
man, q.v. 

23. LENTUS Say 1834. Planorbis lentus Say 1834, 
Amer. Conch. 6:6, PL 4, Fig. 1. (Mexico, Ojo 
de Agua, and Canal at New Orleans, La.) 

24. MEXICANUS "Ziegler"Dunker 1850. Planorbis 
mexicanus "Ziegler" Dunker 1850, Syst. 
Conch. -Cab. Mart, and Chem., Ed. 2, Planorbis, 
p. 45, as a synonym of P. tenuis "Philippi" 
Dunker. No locality. 



25. MINOR von Martens 1899- Planorbis carihaeus 
var. minor von Martens 1899, Biol. Centr. 
Amer., Moll., p. 388. Not figured. ("E. Mexico: 
Vera Cruz in brackish marshes. N. Guatemala: 
Coban"). 

26. MYSAURUS Mabille 1895- Planorbis mysaurus 
Mabille 1895, Bull. Soc. Philomatique Paris, 
8 Ser., 7(2):63-64. Not figured. (LowerCali- 
fornia (Mexico)). Germain, 1921, Cat. Planor- 
bidae, p. 54, decided this is a synonym of 
P. tumidus Pfr., after examining the type. 

27. NICARAGUANUS Morelet 1851- Planorbis 
nicaraguanus Morelet 1851, Test. Noviss. Ins. 
Cub. et Amer. Centr. Pt. 2, p. 14. Not figured 
("H. lacum nicaraguanensem"). 

28. PAUCISPIRATUS Clessin 1885- Planorbis 
paucispiratus Clessin 1885, Syst. Conch. -Cab. 
Mart, and Chem. Ed. 2, Planorbis, p. 223-224, 
PL 33, Fig. 8- (Locality unknown). Von Mar- 
tens, Biol. Centr. Amer., p. 400, noted its re- 
semblance to P. ivyldi Tristram. 

29- PERTENUIS F.C. Baker 1940. Planorbis 
tenuis vat. pertenuis F.C. Baker 1940, Nautilus 
54:97. New name for P. tenuis var. applanatus 
von Martens 1899- 

30. PERUVIANUS Broderip 1832. Planorbis peru- 
vianas Broderip 1832, Proc. Zool. Soc. London 
p. 125, Not figured. ("Hab. in Peruvia (Mala- 
briga, province of Truxillo)"). 

31. SALVINI "Tristram" Clessin 1884. Planorbis 
sö/f»«/ "Tristram" Clessin 1884, Sysc Conch. - 
Cab. Mart, and Chem. Ed. 2, Planorbis, p. 
207-208, PL 31, Fig. 8. ("Centralamerika, 
Guatemala"). 

32. SINUOSUS Bonnet 1864. Planorbis sinuosus 
Bonnet 1864, Rev. et Mag. de ZooL, p. 280, 
PL 22, Fig. 3, 3a. (Rio Grande River, New 
Mexico). Pilsbry (1934:44) thought this is a 
synonym of P. caribaeus d'Orbigny. 

33. SOLIDUS "Wiegmann" von Martens 1899- 
Planorbis solidus "Wiegmann" von Martens 
1899, Biol. Centr. Amer., Moll., p. 384i von 
Martens cites only "Mus. Berol." as the source 
of Wiegmann's name. He proposed the new name 
P. juvenilis to replace it, as P. solidus was 
preoccupied by P. solidus C. Thomae 1845, 
Jahrb. Ver. Nat. Nassau 2:153, and P. solidus 
Dunker 1850 Syst. Conch. -Cab. p. 60. 

34. STREBELIANA Fischer and Crosse 1880- 
Planorbis ancylostomus var. B. Strebeliana 
Fischer and Crosse 1880, Misc. Sei. Мех., 
Moll., 2:63-64. Not figured. (Laguna des Cocos 
and Rio Tenoya, in the state of Vera Cruz 
(Mexico)). 

35. TENUIS "Philippi" Dunker 1850. Planorbis 
tenuis "Philippi" Dunker 1850, Syst. Conch.- 



38 



H. W. HARRY 



Cab. Mart, and Chem., Ed. 2, Planorbis, p. 
45, PI. 9, Figs. 14-16, 17-19 (appeared 1850); 
PI. 16. Fig. 23-25 (appeared 1844, without 
name). ("Häufig in Gräben der Umgegend von 
Mexico mit IJmnaeus subulatus Dkr."). 

36. TUMENS Carpenter 1856. Planorhis tumens 
Carpenter 1856, Cat. Mazatlan Shells in Brit. 
Mus. p. 181. Not figured ("Mazatlan, not com- 
mon"). Carpenter realized this was an extreme- 
ly variable species, and noted that this species, 
P. af finis C.B. Adams and P. lentus Say "may 
hereafter be proved identical." 

37. TUMIDUS Pfeiffer 1839- Planorbis tumidus 
Pfeiffer 1839, ^iegm. Arch. f. Naturgesch. p. 
354, Not figured. (Cuba). The original descrip- 
tion is merely ^'Planorbis tumidus Pfr. Spec- 
imina incompleta, Pi. fragili affina." The 
species is scarecly recognizable froni this 
description, if the name is not nude. 

38. TUMIDUS "Pfeiffer" Dunker 1850. Planorbis 
tumidus "Pfeiffer" Dunker 1850, Syst. Conch. - 
Cab. Mart, and Chem., Ed. 2, Planorbis, p. 39, 
PI. 7, Figs. 10-12. (San Juan and Havana, 
Cuba; Vera Cruz and Vampa, Mexico). P. in- 
termedius Philippi and P. caribaeus d'Orbigny 
are listed as synonyms. The original citation 
of Pfeiffer's is given, but since that is too 
inadequate for recognition, the name should 
date from Dunker's description, as Pilsbry 
(1934) noted. 

39- UHDEI von Martens 1899- Planorbis tenuis v. 
uhdei von Martens 1899» Biol. Centr. Amer., 
Moll., p. 385, PI. 21, Fig. 2. (Central America). 

40. WYLDI Tristram 1861. Planorbis м y W» Tristram 
1861, Proc. Zool. Soc. London p. 232. Not 
figured. ("Lake of Dueñas" (Guatemala)). 



Group of Helisoma eyerdami Clench 
and Aguayo 1932 

41. EYERDAMI Clench and Aguayo 1932. //e/isowa 
eyerdami Clench and Aguayo 1932, Proc. New 
England Zool. Club 13:38. Not figured. ("Lake 
Miragoane, two miles southeast of Miragoane, 
Haiti.") Clench and Aguayo 1937, Mem. Soc. 
Cubana Hist. Nat. 11:68, PI. 7, Fig. 7. 

Two paratypes of this species in the Univer- 
sity of Michigan Museum of Zoology show a 
prominent, thickened keel on both shoulders, 
and a slight flare of the lip in these positions. 
I could not determine whether the embryonic 
whorl was angled. This species seems to be 
distinct from the other Neotropical populations 
of Helisoma, and it may even be a Taphius, 
Anatomical studies are needed to settle the 
question. 



DREPANOTREMATINAE 

Genus Drepanotrema 

Group of Drepanotrema anatinum 
d'Orbigny 

42. ANATINUS d'Orbigny 1835. Planorbis anatinus 
d'Orbigny 1835, Mag. de Zool. V(62):28. Not 
figured. (Rio Parana, Argentina, from the 
stomach of a duck). 1837, Voyage Amer. 
Mérid., p. 351, PI. 45, Figs. 17-20. 

43. ARACASENSIS "Gundlach" Pfeiffer 1879- 
Planorbis aracasensis "Gundlach" Pfeiffer 
1879, Malakozool. Blatt. 4:179- Not figured. 
(Aracas Lake, Tinidad). The original descrip- 
tion consists only of"15. Planorbis Aracasen- 
sis Gund. Eine sehr niedliche und winzige Art 
aus dem See Aracas bei Trinidad." Several 
authors have considered this term a nomen 
nudum. No species could be definitely recog- 
nized from it. 

44. ARACASENSIS "Gundlach" Clessin 1884. 
Planorbis aracasensis "Gundlach" Clessin 
1884, Syst. Conch. -Cab. Mart, and Chem., Ed. 
2, Planorbis, p. 143, PL 15, Fig. 7. (Esperanza, 
Pinos de Rio, Cuba). 

45. ESPERANZENSIS Tryon 1866. Planorhis es- 
peranzensis Tryon 1866, Amer. Jour. Conch. 
2:10, PI. 2, Figs. 11-13 (Esperanza, Cuba). 

46. HALDEMANI C.B. Adams 1849- Planorbis 
haldemani C.B. Adams 1849, Contrib. Conch. 
No. 3, P- 43- Not figured. (Jamaica). 

47. INVOLUTUS "Dunker" Clessin 1884. Planor- 
bis involutus "Dunker" Clessin 1884, Syst. 
Conch. -Cab. Mart, and Chem., Ed. 2, Planorbis, 
p. 143- As a synonym of P. aracasensis 
"Gundlach" Clessin. 

48. ISABEL ".Morelet" Sowerby 1877. Planorbis 
Isabel "Morelet" Sowerby 1877 in Reeve's 
Conch. Icon. V. 20, Planorbis. PI. 12, Fig. 
101. (Locality unknown). Goodrich and van der 
Schalie cite this species from Guatemala 
(1937, Moll. Peten..., p. 33), and Aguayo 
(1933, Nautilus 47:64) considered it a synonym 
of D. anatinum d'Orbigny. 

49. NIGELLUS Lutz 1918. Planorbis (Spiralina) 
nigellus Lutz 1918, Mem. Inst. Osw. Cruz 
10:55- Not figured. (Pool near Manguinhos 
(Brazil)). 

50. YSABELENSIS Crosse and Fischer 1879. 
Planorbis ysabelensis Crosse and Fischer 
1879, Jour. Conchyl. 27:342-343- Not figured. 
(Balancan, province of Tabasco, Mexico, and 
Yzabel, Guatemala). 1880, Miss. Sei. Мех., 
Moll., 2:75-76, PL 33, Fig. 2, 2c. 

^This Subfamily name is here used for the first time. ED. 



A CATALOGUE OF NEOTROPICAL PLANORBIDAE 



39 



Group of Drepanotrema limayanum 
Lesson 

51. AHENUM H.B. Baker 1930. Dre¡>anotrema 
a/'ewMwH.B. Baker 1930,Occ. Pap. Mus. Zool., 
Univ. Mich. 210:49-50, Figs. 2-4 (Bejuma, 
Venezuela). 

52. CATILLUS Anton 1839- Planorbis catillus 
Anton 1839, Verz. d. Conch.... p. 51- Not 
figured. (Lima (Peru)). 

53. DECLIVIS "Gould" Clessin 1884. Planorbis 
declivis "Gould" Clessin 1884, Syst. Conch. - 
Cab. Mart, and Chem., Ed. 2, Planorbis, p. 
142-143, PI. 17, Fig. 3. (Cuba). Not P. declivis 
Genth 1848, nor P. declivis Tate 1869, nor P. 
declivis Sowerby 1877. 

54. FAUSTI Ferguson and Gerhardt 1956. Drepan- 
otrema fausti Ferguson and Gerhardt 1956, 
Bol. Ofic. Sanit. Panamericana 41:340-341, 
Fig. 10, 11. (Sabana Seca, Puerto Rico). 

55. HOFFMANI F.C. Baker 1940. Drepanotrema 
hoffmani F.C. Baker 1940, Nautilus '54:96-97, 
PI. 8. (Isabela, Puerto Rico). 

56. JAMAICENSIS "Dunker" Clessin 1884. Plan- 
orbis jamaicensis "Dunker" Clessin 1884, 
Syst. Conch. -Cab. Mart, and Chem., Ed. 2, 
Planorbis, p. 126. As a synonym of P. surin- 
awews/s "Dunker" Clessin. Not P. jamaicensis 
Bolten 1798. 

57. LANERIANUS d'Orbigny 1841. Planorbis lan- 
ег«дии5 d'Orbigny 1841, in Sagra, Hist. .. Cuba, 
Moll., 1:195, PI. 14, Figs 1-4. (Near Havana, 
Cuba). 

58. LENZI van Benthem Jutting 1943- Anisus 
(Gyraulus) lenzi van Benthem Jutting 1943, 
Arch. f. Hydrobiol. 39:480, text Fig. с and d. 
("Rio S3o Francisco, Sao Pedro Dias-Bucht, 
Pernambuco " (Brazil)). 

59. LIMAYANA Lesson 1830. Planorbis limayana 
Lesson 1830, Voyage autour du monde . . . 
V. 2, Pt. 1, p. 330. Not figured. ("Entre Callao 
et Lima au Pérou" (Peru)). 

60. LUCroUS Pfeiffer 1839. Planorbis lucidas 
Pfeiffer 1839, Wiegm. Arch. f. Naturgesch. p. 
354. Not figured. (Cuba). 

61. MELLEUS Lutz 1918. Planorbis melleus Lutz 
1918. Planorbis melleus Lutz 1918, Mem. Inst. 
Oswaldo Cruz 10:54, PL 16, Fig. 5a,b,c,d. 
(Manguinhos and Meyer in Rio de Janeiro; 
kilometer 22 of the Leopoldina Railway; 
Aracaju; Parahyba (Brazil)). 

62. MENISCUS Guppy 1871. Planorbis meniscus 
Guppy, 1871, Amer. Jour. Conch. 6:310. Not 
figured. (Chatham River, Erin, Trinidad). 

63. PAROPSEIDES d'Orbigny 1835- Planorbis 
paropseides d'Orbigny 1835, Mag. de Zool. 



V(62) p. 27. Not figured. (Province of Lima, 
Republic of Peru). 1837, Voy. Amér. Mérid. p. 
350-351, PI. 45, Figs 5-8. 

64. PURUS von Martens 1868. Planorbis purus von 
Martens 1868, Malakozool. Blatt. 15, p. 190, 
Not figured. (Rodersberg, Jacuhy Region, 
Brazil). 

65. REDFIELDI C.B. Adams 1849. Planorbis red- 
fieldi C.B. Adams 1849, Contrib. Conch. No. 
3, p. 43. Not figured. (Jamaica). 

66. SCHUBARTI Haas 1938. Hippeutis schubarti 
Haas 1938, Arch. f. Molluskenk., 70:49-50, 
Fig. 7 (p. 47). (Acude Triumpho, 1000 m alt.. 
State of Pernambuco, Brazil). 

67. SUCCINEUS Sowerby 1877. Planorbis succineus 
Sowerby 1877, in Reeve's Conch. Icon. Vol. 
20, Planorbis, PI.3, Figs. 19a, b. (No locality). 
It was noted in the index of that volume that 
this entry represents P. redfieldi C.B. Adams, 
and that P. succineus was an error. 

68. SUMICHRASTI Crosse and Fischer 1879. 
Planorbis sumichrasti Crosse and Fischer 

1879, Jour, de Conchyl. 27:342. Not figured. 
(Cacoprieto, Isthmus of Tehuantepec, Mexico). 

1880, Miss. Sei. Мех., Moll., 2:69, PL 33, 
Figs. 6-6d. 

69. SURINAMENSIS "Dunker" Clessin 1884. Plan- 
orbis surinamensis "Dunker" Clessin 1884, 
Syst. Conch. -Cab. Mart, and Chem., Ed. 2, 
Planorbis, p. 126, PL 17, Fig. 11. (Jamaica, 
and the region of Paramaribo, Surinam). 

70. TAENIATUS Morelet 1849. P/a«orèis taeniatus 
Morelet 1849, Test. Noviss. Ins. Cub. et Amer. 
Centr. Pt. 1, p. 17. Not figured. (Isle of Pines 

(Cuba)). 

Group of Drepanotrema kermatoides 
d'Orbigny 

71. ANITENSIS Cooper 1893. Planorbis (Anisus) 
anitensis Cooper 1893, Proc. Calif. Acad. 
Sei. Ser. 2, V. 3, p. 341-342, PL 14, Fig. 8. 
(Santa Anita, Lower California and 10 miles 
from San Jose del Cabo, Lower Calif. (Mexico)). 

72. BARBADENSIS "Dunker" Clessin 1884. Plan- 
orbis barbadensis "Dunker" Clessin 1884, 
Syst. Conch. -Cab. Mart, and Chem., Ed. 2, 
Planorbis, p. 118-119, PL 11, Fig. 4. (Bar- 
bados). 

73. BONARIENSIS Strobel 1874. Planorbis kerma- 
toides bonariensis Strobel 1874, Mat. Malac. 
Argentina, p. 33-34, PL 2, Fig. 1. (Palermo 
and Belgrano, vicinity of Buenos Aires, 
Argentina). 

74. CULTRATUS d'Orbigny 1841. Planorbis cul- 
tratus d'Orbigny 1841, in Sagra, Hist. . . Cuba, 



40 



H. W. HARRY 



Moll., Vol. 1, p. 196, PI. 14, Figs. 5-8. (Cuba? 
probably Martinique). 

75. DEPRESSISSIMUS Moricand 1839- Planorbis 
defrressissimus Moricand 1839, Mém. Soc. 
Phys. Hist. Nat. Genève, 8:143-144, PI. 3, 
Fig. 10, 11. (Bahia, Brazil). 

76. DUENASIANUS Tristram 1861. Planorbis 
duenasianus Tristram 1861, Proc. Zool. Soc. 
London p. 232. Not figured. (Lake of Dueñas 
(Guatemala)). 

77. HARRYI Ferguson and Gerhardt 1956. Drepan- 
otrema harryi Ferguson and Gerhardt 1956, 
Bol. Ofic. Sanit. Panamericana 41:337-340, 
Figs. 4-6 (p. 338) and Fig. 13 (p. 339). (St. 
Croix, Virgin Islands). 

78. KERMATOIDES d'Orbigny 1835- Planorbis 
kermatoides d'Orbigny 1835, Mag. de Zool. 
V(62):27. Not figured. (Province of Lima, 
Peru). 1837, Voy. Amér. Mér., Moll., p. 350, 
PI. 45, Figs. 1-4. 

79. NORONHENSIS Smith 1890. Planorbis noron- 
hensis Smith 1890, Jour. Linn. Soc. Lond. , 
20:502-503, PI- 30, Figs. U-llb. (The lake on 
the southwest corner of Fernando Noronha 
(Brazil)). 

80. PANUCO Pilsbry 1934. Drepanotrema cultratum 
panuco Pilsbry 1934, Proc. Acad. Nat. Sei. 
Phila. 86:60-61, PL 11, Figs. 4-5a. (Pasture 
west of San D i e g u i t o, San Luis Potosi, 
Mexico). 

81. PENINSULARIS Cooper 1893- Planorbis 
(AnisusF) peninsularis Cooper 1893, Proc. 
Calif. Acad. Sei., Ser. 2, 3:342, PL 14, Fig. 9. 
("With P. anitensis, in the same laguna"). 

82. PULCHELLUS "Philippi" Clessin 1884. 
Planorbis pulchellus "Philippi" Clessin 
1884, Syst. Conch. -Cab. Mart, and Chem.,Ed. 2, 
Planorbis, p. 137, PL 11, Fig. 6; PL 16, Figs. 
12-14. (Bolivia). 

83. TANCREDII Paravicini 1894. Planorbis tan- 
credii Paravicini 1894, Boll. Mus. Zool. Anat. 
Comp. Univ. Torino 9(181):8-9. Not figured. 
(Asuncion, Paraguay). 

84. TENUISSIMUS "Philippi" von Martens 1873. 
Planorbis lenuissimus "Philippi" von Martens 
1873, Binn. Moll. Venez., p. 197. As a syno- 
nym of P. cultratus d'Orbigny. 

Group of Drepanotrema cimex Moricand 

85. ANGULATUS Chitty 1853- Planorbis angulatus 
Chitty 1853, Contrib. Conch. No. 1, p. 18-19. 
Not figured. (Near the head of the navigable 
part of Black River, St. Elizabeth (Jamaica)). 
Not. P. angulatus Wood, 1838. See D. chittyi. 

86. BAVAYI Crosse 1875- Planorbis bavayi 
Crosse 1875, Jour, de Conchyl. 23:329. Not 



figured. (Guadeloupe, Antilles). 1876, Jour, de 
Conchyl. 24:388, PL 11, Fig. 3- 

87. CHITTYI Aguayo 1935- Drepanotrema chittyi 
Aguayo 1935, Mem. Soc. Cubana Hist. Nat. 
9:121. New name for Planorbis angulatus 
Chitty 1853, q.v. 

88. CIMEX Moricand 1839- Planorbis cimex Mori- 
cand 1839- Mém. Soc. Phys. Hist. Nat. Genève 
8:143, PI. 3, Figs. 8-9- (Bahia, Brazil). 

89. LABROSUM Pilsbry 1934. Drepanotrema cul- 
tratum labrosum Pilsbry 1934, Proc. Acad. 
Nat. Sei. Phila. 86:61, PL 11, Figs. 9-11. 
(Brownsville, Texas). 

90. MACNABL\NUS C.B. Adams 1849- Planorbis 
macnabianus C.B. Adams 1849, Contrib. Conch. 
No. 3, P- 43- Not figured. (Jamaica). 

91. PISTIAE H.B. Baker 1930. Drepanotrema 
cimex pistiae H.B. Baker 1930, Occ. Pap. 
Mus. Zool., Univ. Mich. 210:50-51, PL 30. 
Fig. 1, (Tucacas, Venezuela). 

92. POEYANUS Clessin 1884. Planorbis poeyanus 
Clessin 1884, Syst. Conch. -Cab. Mart, and 
Chem., Ed. 2, Planorbis, p. 205-206, PL 31, 
Fig. 2. ("Die Antillen; St. Domingo (Coll. 
Dunker) Havannah (Coll. Morelet)"). 

93. UNGULATUS "Chitty" Sowerby 1877. Planor- 
bis ungulatus "Chitty" 1877, in Reeve's 
Conch. Icon. Vol. 20, Planorbis. PL 8, Fig. 
62. (Jamaica). Error for P. angulatus Chitty. 

Group of Drepanotrema heloicus 
d'Orbigny 

94. CASTANEONITENS Pilsbry and Vanatta 1896. 
Planorbis castaneonitens Pilsbry and Vanatta 
1896, Proc. Acad. Nat. Sei. Phila. p. 561-562, 
PL 27, Figs. 10-12. (Ponds and small stream 
near Maldonado, Uruguay). 

95. HELOICUS d'Orbigny 1835. Planorbis heloicus 
d'Orbigny 1835, Mag. de ZooL, V(62):27. Not 
figured. (Montevideo, Uruguay). 1837, Voy. 
Amér. Mérid. p. 349, PL 45, Figs. 9-12. 

This species is probably very circumscribed. 
I have seen material in the U.S. National Mu- 
seum and University of Michigan Museum of 
Zoology which is apparently paratypic of 
Pilsbry and Vanatta's species. The general 
form and color of the shell suggest a species 
close to D. limayanum, yet the absence of any 
spiral sculpture on the shell, and the fact 
that d'Orbigny (1837) says the animal is uni- 
formly blackish in color, leaves much room for 
doubt about its systematic position. 

Genus undescribed: Group of "Planorbis" 
salleanus Dunker 1853 

96. CIRCUMLINEATUS Shuttleworth 1854. Planor- 
bis circumlineatus Shuttleworth 1854. Mitth. 



A CATALOGUE OF NEOTROPICAL PLANORBIDAE 



41 



Naturf. Gesellsch. Bern. p. 96-97- Not figured. 
(Humacao, Puerto Rico). 

97. NORDESTENSIS Lucena 1954. Tropicorbis 
nordestensis Lucena 1954, Rev. Brasil. Malar. 
D. Trop. 6(3):329-331; 1955, Jour, de Conchyl., 
95:20-22. These references I have not seen. 
But see Paraense and Deslandes 1958:281. 

98. SALLEANUSDunlcer 1853- Planorbis salleanus 
Dunker 1853, Proc. Zool. See. Lond. 21:53-54. 
Not figured. (St. Domingo). 

99. SANTACRUZENSIS "Nevill" Germain 1923- 
Planorbis (Gyraulus) santacruzensis "Nevill" 
Germain 1923, Cat. Planorbidae, Rec. Indian 
Museum 21, p. 138-139, Fig. 18-21 (p. 139), 
PI. 4, Figs. 10, 13 and 14. (St. Croix, Virgin 
Islands). 

100. SIMMONSI Ferguson and Gerhardt 1956. Dre- 
panotrema simmonsi Ferguson and Gerhardt 
1956, Bol. Ofic. Sanit. Panamericana 41:336- 
337, Figs. 1-3 (p. 338) and Fig. 12 (p. 339). 
(Sabana Seca and Arroyo, Puerto Rico). 

Genus Acrorbis 

101. PETRICOLA Odhner 1937. Acrorbis petricola 
Odhner 1937, Ark. Zoologi Bd. 29B, No. 14, 
p. 1-8. Ten text figures. (Santa Catharina, 
Brazil). 

TAPHUNAE 
Genus Taphius 
Group of Taphius andecolus d'Orbigny 

102. ANDECOLUS d'Orbigny 1835- Planorbis ande- 
colus d'Orbigny 1835, Mag. de Zool. V(62):26. 
Not figured. ("Habit, lacu Titicaca (república 
Boliviana)"). 1837, Voy. Amér. Mérid., p. 
346, Pl. 44, Figs. 1-4. 

103. CONCENTRATUS Pilsbry 1924. Planorbis 
(Taphius) andecolus concentratus Pilsbry 1924, 
Proc. Acad. Nat. Sei. Phila., p. 50, PI. 4, 
Figs. 2, 2a, 2b. (Lake Titicaca, Peru). 

104. HETEROPLEURUS Pilsbry and Vanatta 1896. 
Planorbis heteropleurus Pilsbry and Vanatta 
1896, Proc. Acad. Nat. Sei. Phila. p. 562, PL 
26, Figs. 1,2 and 3- (Lake Titicaca). 

This species was designated the genotype 
of Platytaphius by Pilsbry 1924, Proc. Acad. 
Nat. Sei. Phila., p. 51. Hubendick (1955, 
1955a) examined the anatomy of this species, 
and failed to note any character of significance 
from Taphius s.s. Haas (1955) considers P. 
heteropleurus to be merely a variant of Taphius 
andecolus d'Orbigny. 

105. LAURICOCHAE Philippi 1869- Planorbis 
lauricochae Philippi 1869, Malakozool. Blatt. 
16:38. Not figured. ("Habitat in lacu andino 



Lauricocha, unde flumen Maranon sive Ama- 
zonas nascitur"). 

106. MONTANUS d'Orbigny 1835- Planorbis mon- 
tanus d'Orbigny 1835, Mag. de Zool. V(62):26. 
Not figured. ("Habitat in lacu Titicaca re- 
publica Boliviana). 1837, Voy. Amér. Mérid., 
p. 345-346, Pl. 44, Figs. 5-8. 

107. PENTLANDI "Valenciennes" Beck 1837. 
Planorbis pentlandi "Valenciennes" Beck 
1837, Index, moll, praes. ... p. II9. Not de- 
scribed or figured. As a synonym of P. ande- 
colus d'Orbigny. 

108. TITICACENSIS Clessin 1884. Planorbis 
titicacensis Clessin 1884, Syst. Conch. -Cab. 
Mart, and Chem., Ed. 2, Planorbis, p. 147, PL 
12, Fig. 23-25. (Lake Titicaca). 

Group of Taphius pronus von 
Martens 1873 

109. COSTATUS Biese 195L Taphius costatus 
Biese 1951, Bol. Mus. Nac. Hist. Nat. (Chile) 
25:116-117, Fig. 5, p. 130; Pl. 6, Figs. 1-3 
("Cuchicha, 3,800 m. de altura" (Chile)). 
Topotypic material identified by Biese in the 
University of Michigan Museum of Zoology is 
apparently of this group. 

110. PRONUS von Martens 1873. Planorbis pronus 
von Martens 1873, Binnenmoll. Venez, p. 198- 
199, PI. 2, Fig. 5. ("Valenciasee" (Vene- 
zuela)). 

111. SOLroULUS Clessin 1885. Planorbis solidulus 
Clessin 1885, Syst. Conch.-Cab. Mart, and 
ehem., Ed. 2, Planorbis. p. 224, PL 33, Fig. 
10 ("?Coll. Morelet"). Of unknown locality, 
this species is included here because von 
Martens, 1899, p. 400 (Biol. Centr. Amer.) notes 
its similarity to his P. />ro«tts and P. subpronus, 
and von Martens claimed he examined Clessin's 
material. 

112. SUBPRONUS von Martens 1899- Planorbis 
(Taphius) subpronus von Martens 1899, Biol. 
Centr. Amer. p. 396, PL 21, Fig. 15- ("S.E. 
Mexico: Amatitan, State of Tabasco"). 

113. TRIGYRUS Philippi 1869- Planorbis trigyrus 
Philippi 1869, Malakazool. Blatt. 16:39. Not 
figured. ("Specimen unicum cum Pl, helophilo 
d'Orb. in litore Peruviae ad Pimentel lectum 
vidi"). 

Group of Taphius caloderma Pilsbry 1923 

114. CALODERMA Pilsbry 1923- Planorbis calo- 
derma Pilsbry 1923, Nautilus p. 143-144. Not 
figured. ("Esmerelda, Guatemala"). F.C. 
Baker 1945, Moll. Fam. Planorbidae, Pl. 115, 
Figs. 2-4, figured cotypes. Anatomical studies 
may show this species to be a Helisoma. 



42 



H. W. HARRY 



Group of Taphius eucosmius Bartsch 1908 

115. EUCOSMIUS Bartsch I9O8. Planorbis eucosmius 
Bartsch 1908, Proc. U.S. Nat. Mus. 33:699- 
PI. 57, Figs. I-3. ("Greenfield Pond, Wilming- 
ton, North Carolina" (U.S.A.)). 

116. VAUGHANI Bartsch 1908. P/awor¿ís eucosmius 
vaughani Bartsch 1908, Proc. U.S. Nat. Mus. 
33:699-700, Pi. 57, Figs. 4-6 ("Burkes Place, 
Louisiana" (U.S.A.)). 

I am indebted to Dr. J. P.E. Morrison for 
calling my attention to the striking similarity 
of these shells to Taphius. The spiral band 
of dark brown color is distinctive, and not found 
in any other planorbid, to my knowledge. 

Group of Taphius glabratus Say 1818 

117. ALBESCENS "Spix" Wagner 1827. Planorbis 
albescens "Spix" Wagner 1827, Test. Fluv. 
Bras. p. 27, as a synonym of P- lugubris 
Wagner, q.v. 

118. ANTIGUENSIS "Guilding" Sowerby 1877. 
Planorbis antiguensis "Guilding" Sowerby 
1877, in Reeve's Conch. Icon. Vol. 20, Planor- 
bis, PI. 12, Figs. lOOa-b. (Antigua, West 
Indies). 

119. ANTILLARUM Beck 1837. Planorbis antillarum 
Beck 1837, Index, moll, praes. . . ., p. 120, 
Refers to Chemnitz, Conch. -Cab., Ed. 1, Vol. 
9, 12th Abt., Fig. 1118. (Antilles). 

120. BECKI Dunker 1850. Planorbis becki Dunker 
1850, Syst. Conch. Cab. -Mart, and Chem., Ed. 
2, Planorbis. p. 48, PL 8, Figs. 4-6 (Brazil) 

121. BLAUNERI "Shuttleworth" Germain 1921. 
Planorbis (Planorbina) blauneri "Shuttleworth" 
Germain 1921, Cat. Planorbidae, p. 47, text 
Fig. 17, and PL 4, Figs. 2 and 7. (Vieques, 
east of Puerto Rico). 

122. BOLIVIANUS "Philippi" Dunker 1850. Planor- 
bis bolivianus "Philippi" Dunker 1850, Syst. 
Conch. -Cab. Mart, and Chem., Ed. 2, Planorbis, 
p. 60 and 408, PL 10, Figs. 35-37. (Bolivia). 

123. CHRISTOPHORENSIS Pilsbry 1934. Australor- 
bis glabratus christophorensis Pilsbry 1934, 
Proc. Acad. Nat. Sei. Phila. 86:58, PL 11, 
Fig. 12. (Saint Christopher (St. Kitts), British 
West Indies). 

124. CONCAVOSPIRA Anton 1839- Planorbis con- 
cavospira Anton 1839, Verz. d. Conch. . ., p. 50- 
51. Not figured. (South America). 

125. CONFUSUS Lutz 1918. Planorbis confusus 
Lutz 1918, Mem. Inst. Oswaldo Cruz 10:49-50, 
PL 15, Figs. 2a-d. (Rio de Janeiro, Brazil). 
New name for P. ferrugineus d'Orbigny 1837, 
Voy. Amer. Me'rid. Lutz thought d'Orbigny had 
erroneously attached the name P. ferrugineus 



Spix to a species which was not that of Spix, 
and which had received no name of its own. 
Not P. confusus Rochebrunne 1881. 

126. CUMINGIANUS Dunker 1848. Planorbis cuming- 
ianus Dunker 1848, Proc. Zool. Soc. London 
p. 41. Not figured. (Locality unknown), 1850, 
Syst. Conch. -Cab. Mart, and Chem., Ed. 2, 
Planorbis, p. 49, PI. 8, Fig. 1-3- (No locality). 
Placed in the synonymy of Pi. olivaceus Spix 
by Germain, 1921, Cat. Planorbidae, p. 45- 

127. DENTIFER Moricand 1853- Planorbis dentifer 
Moricand 1853, Jour, de Conchyl. 4:37. Not 
figured. (Lake Baril, near Bahia, Brazil). See 
Paraense, 1957, Proc. Mai. Soc. London, 32: 175- 

128. FERRUGINEUS "Spix" Wagner 1827. Planor- 
bis ferrugineus "Spix" Wagner 1827, Test. 

Fluv. Bras p. 26, PL 18, Fig. 1. As a 

synonym of P. olivaceus "Spix" Wagner. 

129. GUADALOUPENSIS Sowerby 1822. Planorbis 
guadaloupensis Sowerby 1822, Genera of Re- 
cent and fossil Shells, No. 4. No description. 
(Guadeloupe). 

130. GLABRATUS Say 1818. Planorbis glabratus 
Say 1818, Jour. Acad. Nat. Sei. Phila. p. 280. 
Not figured. ("South Carolina"). Pilsbry (1934) 
argued that the locality was a mistake, and 
that Say's material probably came from Guade- 
loupe. 

131. IMMUNIS Lutz 1923. Planorbis immunis Lutz 
1923, Nautilus 37:36. New name for P. confusus 
Lutz 1918, q.v. 

132. LUGUBRIS Wagner 1827. Planorbis lugubris 

Wagner 1827, Test. Fluv. Bras p. 27, PL 18, 

Figs. 3-6. (Ilheos and Almada, Bahia, Brazil). 

133- LUTESCENS Lamarck 1822. Planorbis lutes- 
cens Lamarck 1822, Anim. Sans Vert. 6(2):153- 
Not figured. Locality unknown. Mermod (1952) 
figures this species, compares it with P. 
guadeloupensis Sowerby, and suggests it comes 
from the Antilles or northern South America. 

134. NIGRICANS "Spix" Wagner 1827. Planorbis 
nigricans "Spix" Wagner 1827, Test, Fluv. 
Bras. ... p. 27. As a synonym of P. lugubris 
Wagner. 

135. OLIVACEUS "Spix" Wagner 1827. Planorbis 
olivaceus "Spix" Wagner 1827, Test. Fluv. 

Bras p. 26, PI. 18 Fig. 1-2. (Ilheos and 

Almada, Bahia, Brazil). 

136. REFULGENS Dunker 1853- Planorbis refulgens 
Dunker 1853, Proc. Zool. Soc. London p. 54. 
Not figured. (St. Domingo). Clessin, 1883, Syst. 
Conch. -Cab. Mart, and Chem., Ed. 2, Planorbis, 
p. 106, PL 18, Fig. 10, PI. 17, Fig. 5. 

137. STRIATULUS "Richard" Beck 1837. Planor- 
bis striatulus "Richard" Beck 1837, Index 



A CATALOGUE OF NEOTROPICAL PLANORBIDAE 



43 



moll, praes. . . ., P- 120. Not figured. As a syn- 
onym of P. guadaloupensis Sowerby with the 
reference "Guer. Jc vii 1 ?" given. I can 
locate nothing in Guerin which would satisfy 
that citation. 

138. VIRIDIS "Spix" Wagner 1827. Planorbis viridis 

"Spix" Wagner 1827, Test. Fluv. Bras p. 27. 

As a synonym of P. lugubris Wagner. 

139. XERAMPELINUS Drouet 1859, Planorbis 
xerampelinus Drouet 1859, Essai Moll. Terr. 
Fluv. Guyane Française p. 76, PI. 2, Figs. 
27-29- (French Guiana). 

Group of Taphius tenagophilus 
d'Orbigny 1835 

140. BAHIENSIS Dunker 1850. Planorbis bahiensis 
Dunker 1850, Syst. Conch. -Cab. Mart, and 
Chem., Ed. 2, Planorbis, p. 51, PL 8, Figs. 
13-18. (Bahia, Brazil). 

141. BIANGULATUS Sowerby 1877. Planorbis bi- 
angulatus Sowerby 1877, in Reeve's Conch. 
Icon. Vol. 20, Planorbis, PI. 4, Fig. 25- (Bra- 
zil). Walker, 1918, Synopsis Freshwater Moll. 
N. Amer., p. 95, considered this species a 
synonym of P. antros us Conrad, but other 
authors, as Lutz, 1918, considered it Brazilian. 

142. CHEMNITZIANA Beck 1837. Planorbis ten- 
agophilus с hemnitziana Beck 1837, Index moll. 

praes , p. 120, cites "C IX 1119-20?" 

evidently referring to the first edition of the 
Syst. Conch. -Cab. of Chemnitz. (Bolivia). 

143. CLEVEI "Jousseaume" Cousin 1887. Planor-^ 
bis clevei "Jousseaume" Cousin 1887, Bull. 
Soc. Zool. France 12:263, PL 4, Fig. 9- 
(Ecuador). 

144. MEGAS Pilsbry 1951. Australorbis bahiensis 
megas Pilsbry 1951, Nautilus 65=4, PL 9, 
Figs. 4,4a and 5 (of Vol. 64: not named there). 
(Petropolis, State of Rio de Janeiro, Brazil). 

145. ORBIGNYANA Beck 1837. Planorbis tena- 
gophilus orbignyana Beck 1837, Index moll, 
praes...., p. 120. (Argentina). Asa subspecies 
of P. tenagophilus, with the citation "d'Orb. 
V xliv 9-12," which is the typical species. 

146. PAYSANDUENSIS Marshall 1930. Planorbis 
paysanduensis Marshall 1930, Proc. U.S. Nat. 
Mus. 77(2):4, PL 1, Figs. 1,4 and 6.(Paysandu, 
Uruguay). 

147. TENAGOPHILUS d'Orbigny 1835. Planorbis 
tenagophilus d'Orbigny 1835, Mag. de Zool., 
p. 347. Not figured. (Province of Corrientes, 
Argentina; Province of Santa-Cruz and Chi- 
quitos, Bolivia). 1837, Voy. Amér. Mérid., p. 
237, PL 44, Figs. 9-12. 



Group of Taphius peregrinus 
d'Orbigny 1835 

148. ARGENTINENSIS Beck 1837. Planorbis pere- 
grinus argentinensis Beck 1837, Index moll, 
praes. . . ., p. 120, as a subspecies of P. pere- 
grinus d'Orbigny. Not figured or described. 
(Pampas (Argentina)). 

149. CANONICUS Cousin 1887. P/ö«ori»s canonicus 
Cousin 1887, Bull. Soc. Zool. France 12:264, 
PL 4, Fig. 11. (Lake Saint Paolo, near Quito, 
Ecuador). 

150. CENTIMETRALB Lutz 1918. Planorbis centi- 
metralis Lutz 1918, Mem. Inst. Oswaldo Cruz 
10:52-53, PL 17, Figs. 8a-d. (Several locali- 
ties in Eastern Brazil, and Paraguay). 

151. CHILENSIS Anton 1839. Planorbis chilensis 

Anton 1839, Verz. d. Conch , p. 51, Not 

figured. (Chile). 

152. LEVISTRIATUS Preston 1912. Planorbis levi- 
striatus Preston 1912, Proc. Mai. Soc. London 
10:107. Figured in text. ("The Miguelete River, 
Montevideo"(Uruguay)). Paratypic material ex- 
amined at the University of Michigan Museum 
of Zoology is evidently this species. (UMMZ 
84088). 

153- LIMAYANUS Beck 1837. Planorbis peregrinus 
limayanus Beck 1837, Index moll, praes. . . ., p. 
120. Not figured. (Lima, Peru). As a subspe- 
cies of P. peregrinus d'Orbigny, without de- 
scription. Not P. limayana Lesson 1830. 

154. MONTANUS Biese 1951. Tropicorbis montanus 
Biese 1951, Bol. Mus. Nac. Hist. Nat. (Chile), 
25:125-126. Fig. 3, p. 130; PL 6, Figs. 13-15. 
(Rio Hurtado, Samo Alto, Prov. de Coquimbo 
(Chile)). Paratypic material in the University 
of Michigan Museum of Zoology (UMMZ 183447) 
is evidently this species. 

155- PATAGONICUS Beck 1837. Planorbis pere- 
grinus patagonicus Beck 1837, Index moll, 
praes...., p. 120. Not figured. (Patagonia). 
As a subspecies of P. peregrinus, without 
description. 

156. PEDRINUS Miller 1879. Planorbis (Taphius) 
pedrinus Miller 1879, Malakozool. Blatt, n.f., 
26:148, PL 7, Figs. 3aA,C. ("Chillo, Rio S. 
Pedro" (Ecuador)). 

157. PEREGRINUS d'Orbigny 1835. Planorbis pere- 
grinus d'Orbigny 1835, Mag. de Zool. V(62): 
26-27. Not figured. ("Habit. Patagonia, Monte- 
video (república Uruguayensi orientali); Pam- 
pas; provincia Corrientes (república Argentina); 
provincia Rio-Grande (república Boliviana) et 
provincia Guayaquilensi (república Columbi- 
ana)"). 1837, Voy. Amér. Merid. p. 348, PL 
44, Figs. 13-16. 



44 



H. W. HARRY 



158. PUCARAENSIS Preston 1909- Planorbis рис- 
araensis Preston 1909, Ann. Mag. Nat. Hist. 
Ser. 8, 3:512, PI. 10, Fig. 15, ("Pucará, Peru, 
at an altitude of 12,500 feet"). Paratypic ma- 
terial in the University of Michigan Museum of 
Zoology (UMMZ 89735) is evidently this 
species. 

159- SCHMIERERIANUS Biese 1951. Tropicorbis 
schmiererianus Biese 1951, Bol. Mus. Nac. 
Hist. Nat. (Chile) 25:122-124, Fig. 2, p. 130; 
PI. 6, Figs. 10-12. ("Salamanca, Rio Choapa" 
(Chile). Several other localities are given). 
Several lots in the University of Michigan Mu- 
seum of Zoology, identified by Biese from the 
localities he cited, are evidently this species. 

160. STRAMINEUS Dunker 1848. Planorbis stramin- 
eus Dunker 1848, Proc. Zool. Soc. London p. 
42. Not figured. (South America). 1850, Syst. 
Conch. -Cab. Mart, and ehem., Ed. 2, Planorbis, 
p. 42, PI. 5, Figs. 7-9. 

Group of Taphius albicans Pfeiffer 

161. ALBICANS Pfeiffer 1839. Planorbis albicans 
Pfeiffer 1839, Wiegm. Arch. f. Naturgesch. p. 
354. Not figured. (Cuba). 

162. ARAKANENSIS "Gould" Sowerby 1877. Planor- 
bis arakanensis "Gould" Sowerby 1877 in 
Reeve's Conch. Icon. Planorbis, PI. J2, No. 
100. (Trinidad). 

163. BERENDTII Tryon 1866. Planorbis (Planor- 
bula) berendtii Tryon 1866, Amer. Jour. Conch. 
2:10, PI. 2, Figs. 14-16. ("Vera Cruz, Mexico; 
Orizaba, Mexico"). 

164. CANNARUM Morelet 1849. Planorbis cannarum 
Morelet 1849, Test. Noviss. Ins. Cub. et Amer. 
Centr. Pt. 1, p. 16. Not figured. ("H. Belise, 
in littore Hondurasano"). 

165. DECLIVIS Tate 1870. Planorbis declivis Tate 
1870. Amer. Jour. Conch. 5:159. Not figured. 
(Acoyapa, Nicaragua). F.C. Baker 1940, 
Nautilus 54(3):97, renamed this P. tatei, as 
Tate's name was preoccupied by P. declivis 
Genth, 1848. 

166. DENTATUS Gould 1844. Planorbis dentatus 
Gould 1844, Boston Jour. Nat. Hist. 5:496, 
PI. 24, Fig. 14. ("small lagoon at San Jorge" 
(Cuba)). 

167. DENTIENS Morelet 1849. Planorbis dentiens 
Morelet 1849, Test. Noviss. Ins. Cub. et Amer. 
Centr. Pt. l,p. 18. Not figured. ("H. paludosa 
circa Belize, in littore Hondurasano"). 

168. DENTIFERUS C.B. Adams 1845. Planorbis 
dentiferus C.B. Adams 1845, Proc. Boston 
Soc. Nat. Hist. 2:17. Not figured. (Jamaica). 

169- DONBILLI Tristram 1861. Sementina donbilli 



Tristram 1861, Proc. Zool. Soc. London p. 
232. Not figured. ("Lake of Dueñas" (Guate- 
mala)). 

170. DUNKERIANUS Clessin 1884. Planorbis dun- 
kerianus Clessin 1884, Syst. Conch. -Cab. 
Mart, and Chem., Ed. 2, Planorbis, p. 122, 
PI. 17, Fig. 14. ("Insel Cuba, San Juan"). 

171. EDENTATUS C.B. Adams 1851. Planorbis 
dentiferus edentatus C.B. Adums 1851, Contrib. 
Conch. No. 8, p. 132. Not figured. (Jamaica, 
Hatfield in Westmoreland). 

172. EDENTULA Fischer and Crosse 1880. Planor- 
bula dentiens var. edentula Fischer and Crosse 
1880, Miss. Sei. Мех. Moll. 2:80-81, PL 34, 
Figs. 6-6c. ("Colonie Anglaise de Belize"). 

173. EDENTULUS Clessin 1884. Planorbis edentu- 
lus Clessin 1884, Syst. Conch. -Cab. Mart, and 
Chem., Ed. 2, Planorbis, p. 220-221, PL 33, 
Fig. 2. ("Central Amerika"). 

174. GEOSCOPUSPilsbryand Brown 1914. Segmen- 
tina obstructa geoscopus Pilsbry and Brown 
1914, Proc. Acad. Nat. Sei. Phila. p. 431, 
PI. 14, Figs. 4-5. (Antigua). 

175. INCERTUS Lutz 1918. Planorbis (Taphius) 
incertus Lutz 1918, Mem. Inst. Oswaldo Cruz, 
10, p. 54, PL 17, Fig. 9a,b,c, and lOd. (Para- 
hyba and Pernambuco, Brazil). 

176. INCERTULUS "Lutz" Paraenseand Deslandes 
1956. Planorbis incertulus "Lutz" Paraense 
and Deslandes 1956, Rev. Brasil. Biol. 16 
(l):96(From amuseum label of Lutz's, evident- 
ly for P. incertus Lutz). 

177. INSULARUM Pilsbry 1942. Tropicorbis havan- 
ensis insularum Pilsbry 1942, Nautilus 56:8, 
PL 1, Fig. 15. (Grand Cayman Island). 

178. JANEIRENSIS Clessin 1884. Planorbis jan- 
eirensis Clessin 1884, Syst. Conch. -Cab. Mart, 
and Chem., Ed. 2, Planorbis, p. 123, PL 18, 
Fig. 8. ("Rio Janeiro in Brasilien"). 

179. NIGRILABRIS Lutz 1918. Planorbis (Taphius) 
nigrilabris Lutz 1918, Mem. Inst. Oswaldo 
Cruz 10:53, PI. 16, Fig. 6a,c,d. (Rio de Jan- 
eiro; Bahia and Natal, Brazil). 

180. PAPARYENSIS F. Baker 1914. Segmentina 
paparyensis F. Baker 1914, Proc. Acad. Nat. 
Sei. Phila., p. 662-663, PI. 26, Figs. 9-11. 
("Near the mouth of the main affluent of 
Papary Lake"(Brazil)). 

181. PLANULATUS Clessin 1884. Planorbis planu- 
latus Clessin 1884, Syst. Conch. -Cab. Mart, 
and Chem., Ed. 2, Planorbis, p. 163, PL 24, 
Fig. 8. (St. Thomas). 

182. SHIMEKIF.C. Baker 1945. Trop»cor¿>is shimeki 
F.C. Baker 1945, Moll. Fam. Planorbidae, 



A CATALOGUE OF NEOTROPICAL PLANORBIDAE 



45 



p. 218-219, PI. 134, Figs. 12-14, 28. ("Ome- 
tope, Nicaragua"). Páratypes in the U.S. Na- 
tional Museum (USNM 534290) show this 
species is P. albicans Pfeiffer. 

183. SCHRAMM! Crosse 1864, Planorbis schrammt 
Crosse 1864, Jour, de Conchyl. 12:153, PI- 7, 
Fig. 2 (Guadeloupe). 

184. STAGNICOLA Morelet 1851- Planorbis stag- 
nicola Morelet 1851, Test. Noviss. Inc. Cub. 
et Amer. Centr. Pt. 2, p. 14-15, Not figured. 
("H. paludosa littoris cubensis, ad portem 
Bahia-Honda"). 

185. TATEI F.C. Baker 1940. Tropicorbis tatei 
F.C. Baker 1940, Nautilus 54:97. New name 
for Planorbis declivis Tate 1869, q.v. 

Group of Taphius havanensis 
Pfeiffer 1839 

186. ANODONTA Pilsbry 1919. Planorbula obstructa 
anodonta Pilsbry 1919, Proc. Acad. Nat. Sei. 
Phila. , p. 219. Not figured. (Reservoir four 
miles nocth of Guatemala City). 

187. DUNKERI F.C. Baker. Tropicorbis orbiculus 
dunkeri F.C. Baker 1945, Moll. Fam. Planor- 
bidae, p. 494 (Explanation of Plate 129). PL 
129, Figs. 26-31, 32-36. (Dry pool near Tam- 
pico, Mexico, for Figs. 26-31, and "Los 
Canoas, Mexico" for Figs. 32-36). Proposed 
merely as a "new name," with no mention of 
what it was to replace. Probably meant to re- 
place P. haldemani Dunker, q.v. 

188. HALDEMANIDunker 1850. P/íi«or¿>/s haldemani 
Dunker 1850, Syst. Conch. -Cab. Mart, and 
Chem., Ed. 2, Planorbis. p. 59, PL 10, Figs. 
38-40. (Mexico). Not P. haldemani C.B. Adams 
1849. 

189. HAVANENSIS Pfeiffer 1839. Planorbis havan- 
ensis Pfeiffer 1839, Wiegm. Arch. F. Na- 
turgesch. p. 354. Not figured. (Havana, Cuba). 

190. LIEBMANNI Dunker 1850. Planorbis liebmanni 
Dunker 1850, Syst. Conch. -Cab. Mart, and 
Chem., Ed. 2, Planorbis, p. 59, PI- 10, Figs. 
32-34. ("Vera Cruz"(Mexico)). 

191. MICROMPHALUS "Dunker" Strebel 1873. 
Planorbis micromphalus "Dunker" Strebel 
1873, Beitr. z. Kenntnis d. Fauna Мех. Land-u. 
SÜSSW. -Conch, p. 47. Not figured. (No locality). 
Said by Strebel to be a juvenile of P. haldemani 
Dunker. 

192. OBSTRUCTUS Morelet 1849. Planorbis ob- 
structus Morelet 1849, Test. Noviss. Ins. 
Cub. et Amer. Centr. Pt. 1, p. 17. Not figured. 
("H. insulam Carmen"). 

193. OBVOLUTUS Clessin 1884. Planorbis obvolu- 
tus Clessin 1884, Syst. Conch. -Cab. Mart, and 



Chem., Ed. 2, Planorbis. p. 222-223, PI. 33, 
Fig. 7. ("Havanah" (Cuba)). 

194. ORBICULUS Morelet 1849. Planorbis orbiculus 
Morelet 1849, Test. Noviss. Ins. Cub. et Amer. 
Centr. Pt. 1, p. 17. Not figured. ("H. insulam 
Carmen et pagum Palizada yucataneorum"). 

195. RIISEI "Dunker" Clessin 1883. Planorbis 
riisei "Dunker" Clessin 1883, Syst. Conch. - 
Cab. Mart, and Chem. Ed. 2, Planorbis, p. 110, 
PI. 17, Fig. 7. ("Jamaica, Puerto Rico"). 

196. STRICTUS Clessin 1885. Planorbis strictus 
Clessin 1885, Syst. Conch. -Cab. Mart, and 
Chem., Ed. 2, Planorbis. p. 223, PI- 33, Fig. 
4. ("'(Central Amerika?) Coll. Morelet"). 

197. TEPICENSIS von Martens 1899. Planorbis 
tepicensis von Martens 1899, Biol. Centr. 
Amer. p. 393, PI. 21, Fig. 14. (N.W. Mexico: 
Tepic, State of Jalisco). 

198. TERVERIANUS d'Orbigny 1841. Planorbis 
terverianus d'Orbigny 1841, in Sagra, Hist. 
Cuba, Moll., 1:194-195, PL 13, Figs. 20-23. 
("environs de la Havane" (Cuba)). 

199. WEINLANDI Pfeiffer 1876. Planorbis ueinlandi 
Pfeiffer 1876, Malakozool. Blatt. 23:172, 232, 
PL 2, Figs. 9-11, (Mountain streams near 
Jeremie, Haiti). 

Group of Taphius helophilus 
d'Orbigny 1835 

200. ATACAMENSIS Biese 195 1. Tro/)ícor¿>»s ataca- 
mensis Biese 1951, Bol. Mus. Nac. Hist. Nat. 
(Chile) 25:126-127, Fig. 4, page I3O; PL 6, 
Figs. 16-18. ("Holotipo: Rio Copiapo. Copiapo 
(Canal Ojances) Prov. de Atacama, 370 m. de 
Atacama, 370 m. de altura" (Chile)). 

201. HELOPHILUS d'Orbigny 1835. Planorbis helo- 
philus d'Orbigny 1835, Mag. de Zool. V(62):27. 
Not figured. ("Habit, provincia Limacensi 
(república Peruviana)"). 1837, Voy. Amér. Mérid. 
p. 349, PL 45, Figs. 13-16. 

202. INFLEXUS Paraense and Deslandes 1956. 
Australorhis inflexus Paraense and Deslandes 
1956, Rev. Brasil. Biol. 16:149-158, text Figs. 
1-7. ("Type locality; Pouso Alegre, State of 
Minas Gerais, Brazil"). 

203. URUGUAYENSIS Preston 1912. Planorbis 
uruguayensis Preston 1912, Proc. Mai. Soc. 
London 10:107. Figured in text. ("Montevideo" 
(Uruguay)). 

Group of Taphius pallidus 
C. B. Adams 1846 

204. DECIPIENS C.B. Adams 1849. Planorbis de- 
cipiens C.B. Adams 1849, Contrib. Conch. 
No. 3, pp. 43-44. Not figured. (Jamaica). 



46 



H. W. HARRY 



205. ISTHMICUS Pilsbry 1920. Planorbis isthmicus 
Pilsbry 1920, Nautilus 33:78-79, Text figure. 
(Panama City). 

206. MAYA Morelet 1869- Planorbis maya Morelet 
1849, Test. Noviss. Ins. Cub. et Amer. Centr. 
Pt. 1, p. 16. Not figured. ("H. cisternae 
civitatis Campeche" (Mexico)). 

207. PALLIDUS C.B. Adams 1846. Planorbis pal- 
lidas C.B. Adams 1846, Proc. Boston Soc. Nat. 
Hist. 2:102. Not figured. (Jamaica). 

SPECIES INCERTAE SEDIS 

The species listed here are placed in this cate- 
gory for several reasons. In some instances I have 
not been able to recognize them from the descrip- 
tions. In other cases the species seem quite dis- 
tinct, conchologically (e.g., Promenetus minutus 
Taylor), yet I am uncertain of the genus in which it 
should be placed. It is quite possible that additional 
genera will be discovered in the area, which are not 
yet recognized. 

There are among these species several which are 
smaller than any Neotropical species for which the 
anatomy is known, except AcrorAi's /)е/г«со/а Odhner. 
This group includes P. hindsianus Dunker, P. 
panamensis Dunker, P. pfeifferi Strobe!, P. pfeifferi 
mendozanus Strobel, P. boetzkesi Miller and Pro- 
menetus minutus Taylor. Such material is very rare 
in the museum collections which I have studied. 
These species have probably been overlooked in the 
field. 

208. AERUGINOSUS Morelet 1851. Planorbis 
aeruginosus Morelet 1851, Test. Noviss. Ins. 
Cub. et Amer. Centr. Pt. 2, p. 15- Not figured. 
("H. paludosa circa lacum yzabalensem" 
(Guatemala)). 

209- BOETZKESI Miller 1879. Planorbis (Gyraulus) 
boetzkesi Miller 1879, Malakozool. Blatt, n.f. 
26:148, PI. 7, Figs. 4a-A-C. ("Chillo, Rio S. 
Pedro cum praecedenti, crebrior" (Ecuador)). 

210. BOUCARDIANUS Preston 1907. Planorbis 
boucardianus Preston 1907, Ann. Mag. Nat. 
Hist., Ser. 7, 20:497, text Fig. 17, p. 493 
(Mexico). 

211. CIRCULARIS Clessin 1884. Planorbis circu- 
laris Clessin 1884, Syst. Conch. -Cab. Mart, 
and Chem., Ed. 2, Planorbis. p. 221, PI. 33, 
Fig. 3- ("Central Amerika?"). 

212. DENTIFER Morch 1833- Planorbis dentifer 
Morch 1833, Jour. Petit., No. 1, p. 37 (Bahia, 
Brazil). I have not been able to locate this 
reference. It is possibly a nude name, intro- 
duced by Hupe (1854, p. 61), who gave only the 
information cited here. Not P. dentifer Moricand 
1853. 

213. FIELDII Tryon 1863- Planorbis fieldii Tryon 



1863, Proc. Acad. Nat. Sei. Phila., p. 146, PI. 

1, Figs. 4-5- ("Panama"). 

214. FILOCINCTUS Pilsbry and Ferriss 1906. P/önor- 
bis filocinctus Pilsbry and Ferriss 1906, Proc. 
Acad. Nat. Sei. Phila., p. 165, PI- 9, Figs. 
1-3- (San Pedro River, Benson, Arizona, in 
drift debris). Possibly a synonym of one of the 
Neotropical species. 

215. FUSCUS Dunker 1848. P/««orèis fuscus Dunker 
1848, Proc. Zool. Soc. London p. 42. Not 
figured. (Valparaiso (Chile)). 1850, Syst. 
Conch. -Cab. Mart, and Chem., Ed. 2, Planorbis, 
p. 52, PI. 8, Figs. 19-21. 

216. GRACILENTUS Gould 1855. Planorbis gracil- 
entus Gould 1855, Proc. Boston Soc. Nat. Hist. 
5:129. Not figured. ("Great Colorado Desert 
lowlands" (U.S.A.)). Binney, 1865, Land and 
fresh water shells of N. Amer., Pt. 2, p. 108, 
considered this a synonym of P. liebmanni 
Dunker, after examining authentic specimens 
received from Gould. Other writers have con- 
sidered the two species distinct. 

217. GUNDLACHI "Dunker" Clessin 1884. Planor- 
bis gundlachi "Dunker" Clessin 1884, Syst. 
Conch. -Cab. Mart, and Chem., Ed. 2, Planorbis, 
p. 146, PI. 17, Fig. 8. ("Die Insel Trinidad"). 

218. HINDSIANUS Dunker 1848. Planorbis hindsianus 
Dunker 1848, Proc. Zool. Soc. London 16:41. 
Not figured. ("In insulam Puna in sinu ad 
Guayaquil" (Ecuador?)). 

219. HONDURASENSiS Clessin 1884. Planorbis 
hondurasensis Clessin 1884, Syst. Conch. -Cab. 
Mart, and Chem., Ed. 2, Planorbis, p. 164, PI. 
24, Fig. 2. ("Honduras bei Sta. Maria"). 

220. JACOBEANUS "Valenciennes" Hupe 1854. 
Planorbis jacobeanus "Valenciennes" Hupe 
1854, Moluscos, Gay's Hist. Fisica y Politica 
de Chile, p. 124. Not figured. ("Estanques de 
Santiago" (Chile)). 

221. KUHNERIANUS "Dunker" Clessin 1883. 
Planorbis kuhnerianus "Dunker" Clessin 
1883, Syst. Conch. -Cab. Mart, and Chem., Ed. 

2, Planorbis. p. 108, PI. 11, Fig. 12. (Surinam), 

222. KUHNL\NA "Dunker" Clessin 1886. Planorbis 
kuhniana "Dunker" Clessin 1886, Syst. Conch. - 
Cab. Mart, and Chem., Ed. 2, Planorbis, p. 413 
and errata. A proposed substitute for P. kuhner- 
ianus "Dunker" Clessin 1883- 

223. MENDOZANUS Strobel 1874. P/a«or¿)ís (Gyraul- 
us) pfeifferi Strobel, var. mendozanus Strobel 
1874, Mat. Mai. Argent, p. 39-40, PI. 2, Fig. 

3, ("ban Carlos e Manantial de la Pirca nella 
Sierra de Mendoza" (Argentina)). 

224. MERIDAENSIS Preston 1907. Planorbis meri- 
daensis Preston 1907, Ann. Mag. Nat. Hist., 



A CATALOGUE OF NEOTROPICAL PLANORBIDAE 



47 



Ser. 7, 20:497, Fig. 18 (p. 493). (Merida, 
Yucatan). 

225. MEXICANUS "Dunker" Clessin 1886. Planor- 
bis mexicanus "Dunker" Clessin 1886, Syst. 
Conch. -Cab. Mart. andChem., Ed. 2, Planorbis, 
p. 408, PI. 12, Figs. 1-3. ("Mexico? (nach der 
Benennung der Art.)"). 

226. MINUTUS Taylor 1954. Promenetus minutus 
Taylor 1954 Revista Soc. Mal. "Carlos de la 
Torre," Havana, 9:37-38. Not figured. ("Allee 
Stream, opposite laboratory, Barro Colorado 
Id., Gatun L., Panama Canal Zone"). 

227. MORELETIANUS Clessin 1884- Planorbis 
moreletianus Clessin 1884, Syst. Conch. -Cab. 
Mart, and Chem., Ed. 2, Planorbis, p. 162, PI. 
24, Fig. 1. (La Guayara, Venezuela). 

228. PANAMENSIS Dunker 1848. Planorbis panamen- 
sis Dunker 1848, Proc. Zool. Soc. London 16: 
41. Not figured. ("Hab. in rivulis Panama 
(H. Cuming)"). 

229. PERFORATUS Anton 1839- Planorbis perfora- 
tus Anton 1839, Verz. d. Conch...., p. 51. 
Not figured. ("Lima" (Peru)). 

230. PERUVL\NUS "Mühl." Anton 1839- Planorbis 
peruvianas "Mühl." Anton 1839, Verz. d. 
Conch. . . ., p. 50. Not figured. As a synonym of 
P. neglectus, with no author cited for the latter. 
(Malabrya in Peru). 

231. PETENENSIS Morelet 1851- Planorbis petenen- 
sis Morelet 1851, Test. Noviss. Ins. Cub. et 
Amer. Centr. Pt. 2, p. 15- Not figured. ("H. 
lacum ytza Petenensium" (Guatemala)). 

232. PFEIFFERI Strobel 1874. Planorbis pfeifferi 
Strobel 1874, Mat. Mai. Argent, p. 39-40, PI- 
2, Fig. 2. ("Belgrano e Tigre presso Buenos 
Aires" (Argentina)). Not Planorbis pfeifferi 
Krauss 1848, Sndafrik. Moll. p. 79. 

233. PHILIPPIANUS Dunker 1848. Planorbis philip- 
pianus Dunker 1848, Proc. Zool. Soc. London 
p. 43, Not figured. (Cochabamba, Bolivia). 
1850, Syst. Conch. -Cab. Mart, and Chem, Ed. 
2, Planorbis, p. 47, PI. 5, Figs. 16-18. 

234. PLANUS CLESSIN 1884. Planorbis planus 
Clessin 1884, Syst. Conch. -Cab. Mart, and 
Chem., Ed. 2, Planorbis, p. 222, PI. 33, Fig. 
6. ("?(Central-Amerika, Coll. Morelet)"). 

235- RAIMONDI Philippi 1869. Planorbis raimondi 
Philippi 1869, Malakazool. Blatt. 16:38-39. Not 
figured. ("In rivulis nemorum loco Peruviae 
dicto 'Pampa del Sacramento' lectus"). 

236. RETUSUS Morelet 1849. Planorbis retusus 
Morelet 1849. Test. Noviss. Ins. Cub. et Amer. 
Centr. Pt. 1, p. 17. Not figured. ("H. insulam 
Carmen"). 

237. SONORENSIS J.G. Cooper 1893- Helicodiscus 



lineatus sonorensis J.G. Cooper 1893, Proc. 
Calif. Acad. Sei., Ser. 2, 3:343, PI. 14. Figs. 
lOa-d. (Near San Miguel, Sonora, Mexico). This 
may be a synonym of P. salleanus Dunker. 
Pilsbry(1948, Land Moll. N. Amer., 2:631-632) 
reproduced the original figure, noted that the 
type was lost, and suggested it belonged to the 
Planorbidae. 

238. THERMALUS Biese 1951- Taphius thermalus 
Biese 1951, Bol. Mus. Nac. de Hist. Nat. 
(Chile), 25:118-119, Fig. 6, p. 130; PI. 6, 
p. 130; PI. 6, Figs. 4-6. ("Holotipo: Ojos de 
Ascotan, Salar Ascotan" (Chile)). 

239. UMBILICATUS Anton 1839. Planorbis umbili- 
catus Anton 1839, Verz. à. Conch...., p. 51. 
Not figured. (Chile). Not P. umbilicatus MUller 
1777. Biese, 1951, suggested Anton's name be 
suppressed, since he found nothing in Chile 
to fit it. 

NOMINA NUDA 

The matter of definition of this category is debat- 
able. Some students hold the view that if anything 
at all is said about a species in naming it as new, 
that name is not nude. Yet much may be said, and 
that species still not be recognizable. In the pres- 
ent list names are considered nude when nothing 
more was said about them than a mere listing of a 
locality, or when only the name itself indicated the 
proposed species came from the Neotropics. 

240. BRAZILIANUS Jay 1836. Planorbis brazilianus 
Jay 1836, Catalogue Ed. 2, p. 77. No descrip- 
tion, figure, citation or locality. 

241. CAPILLARIS Beck 1837. Planorbis capillaris 
Beck 1837, Index moll, praes. . . ., p. 119- No 
citation, description or figure. (Mexico). 

242. COSTATUS "Férussac" Beck 1837. Planorbis 
costatus "Fe'russac" Beck 1837 Index moll, 
praes...., p. 120. No citation, description or 
figure. (Brazil). 

243- CUMINGII Beck 1837. Planorbis cumingii 

Beck 1837, Index moll, praes , p. 120. No 

citation, description or figure. (Chile). Germain, 
1921, Cat. Planorbidae, p. 45, listed this as 
synonym of P. chilensis Anton 1839- 

244. LINNAEUS "Moricand" Hupe 1857. Planorbis 
linnaeus "Moricand" Hupe 1857, Mollusques, 
in Castelnau's Animaux. . . de l'Amérique du 
Sud, p. 62. No citation, description or figure. 
(Brazil). 

245. LUNDII Beck 1837. Planorbis lundiiBecV. 1837, 

Index moll. praes , p. 120. No citation, 

description or figure. (Brazil). 

246. MINUTULUS Beck 1837. Planorbis minutulus 
Beck 1837, Index moll. praes , p. 120. No 



48 



H. W. HARRY 



citation, description or figure. (Antilles). 

247. MORICANDI Beck 1837. Planorbis moricandi 
Beck 1837, Index moll. praes. . . ., p. 120. No 
citation, description or figure. ( Bahia (Brazil)). 

248. REVENTLOWI Beck 1857. Planorbis reventloui 
Beck 1837, Index moll. praes. . . ., p. 120. No 
citation, description or figure. (Rio Janeiro 
(Brazil)). 

249. ROTA Beck 1837. Planorbis rota Beck 1937, 
Index moll. praes...., p. 120. No citation, 
description or figure. (Peru). 

250. SIMPLEX Beck 1837. Planorbis simplex Beck 
1837, Index moll. praes. . . ., p. 120. No cita- 
tion, description or figure. (Mexico). 

EXTRALIMITAL SPECIES 

Besides the names listed here, several African 
species have been cited from the Neotropics. These 
are omitted from the present catalogue. For a dis- 
cussion of the question of the conspecificity of the 
African and Neotropical planorbids, see Paraense 
and Deslandes (1956a). 

251. CORNEUS Linné 1758. Helix cornea Linné 
1758, Syst. Naturae Ed. 10, p. 770. This Eu- 
ropean species, now placed in the genus 
Planorbarius, has been cited from Cuba 
(Aguayo, 1935, Mem. Soc. Cub. Hist. Nat. 
9:120, as Planorbis) and Puerto Rico (various 
papers on parasitology by Hoffmann). These 
records were probably based on specimens of 
Helisoma. There is no convincing account of 
Planorbarius corneus L. from anywhere in the 
New World. 

252. JAMAICENSIS "Bolten" Roding 1798. Planor- 
bis jamaicensis "Bolten" Roding 1798, Mus. 
Boltenianum, p. 73- Refers to Gmelin, Chem- 
nitz and Seba. (Jamaica). This species is the 
first one placed in the genus Planorbis, to be 
cited from the Neotropics. It is a member of 
the Pleurodontidae. 

253.. PARVUS Say 1817. Planorbis parvus Say 1817, 
Nicholson's Encyclopedia Ed. 1, no pagination. 
PI. 1, Fig. 5- (Delaware (U.S.A.)). Cited from 
Mexico byPilsbry (1891, Proc. Acad. Nat. Sei. 
Phila., p. 322), but von Martens (1899, Biol. 
Centr. Amer., Moll., p. 394) notes it is strange 
that noone else has found it in Mexico. Aguayo 
(1938, Mol. Fluv. Cubanos) listed it from Cuba, 
with no specific location or comment. I have 
seen a small lot from Chihuahua (Mexico) and 
two from Cuba, both in the U.S. National Mu- 
seum, but the occurrence of this species in 
the Neotropics needs confirmation. 

254. AMPHIGLYPTUS Pilsbry 1951. Australorhis 



amphiglyptus Pilsbry 1951, Nautilus 65:3, PI. 
9, Figs. 6, 6a (of Vol. 64, where they were 
not named). ("Rio de Janeiro, Brazil" with 
doubt). This is probably the juvenile of some 
land snail. 



BffiLIOGRAPHY 

ADAMS, C. В., 1845, Specierum novarum con- 

chyliorum in Jamaica repertorum, synopsis. 

Proc. Boston Soc. Nat. Hist. 2:1-28. 
, 1846, (Minutes of the meeting of 18 

February 1846). Proc. Boston Soc. Nat. 

Hist. 2:102-103. 
, 1849, Descriptions of supposed new 



species of freshwater shells which inhabit 
Jamaica. Contrib. to Conchol. No. 3, pp. 
42-45. 
, 1851, Descriptions of new varieties 



of shells, which inhabit Jamaica. Contrib. 

to Conchol. No. 8, pp. 129-140. 
ADAMS, H. and A.ADAMS, 1853-1858 .The genera 

of recent Mollusca. London. 3 Vols. (Plan- 

orbidae in Vol. 2), 
AGUAYO, С. G., 1933, On the synonymy and dis- 
tribution of Planorbis- anatinns 6.^ Orbigny. 

Nautilus 47:64-68. 
, 1935, Esplcilegio de moluscos 

Cubanos. Mem. Soc. Cubana Hist. Nat. 9: 

107-128 

, 1938, Los moluscos fluviátiles 

Mem. Soc. Cubana Hist, Nat. 12: 



Cubanos. 
203-242. 

ANTON, H. E., 1839, Verzeichniss der Conchy- 
lien welche sich in der Sammlung von Herman 
Eduard Anton befinden. Halle, i-xii, 1-110. 

BAKER, F. C, 1940, A new species of öre/)ano- 
trema and some preoccupied planorbid 
names. Nautilus 54:96-97. 

, 1945, The molluscan family Plan- 

orbidae. Univ. Illinois Press, Urbana, xxxvi, 
1-530, Pis. 1-141, 

BAKER, Fred, 1914, The land and freshwater 
mollusks of the Stanford Expedition to Brazil. 
Proc. Acad. Nat. Sei. Phila. (1913) 618-672, 
Pis. 21-27. 

BAKER, H. В., 1930, The mollusca collected by 
the University of Michigan— Williamson Elx- 
pedition in Venezuela. Occ, Pap. Mus. Zool. , 
Univ. Mich. No. 210:1-94, 

, 1947, Clessin' s section of Ptoworöfs 

armigeriis. Nautilus 61:71-72. 

BARTSCH, P., 1908, Notes on the fresh- water 
moUusk Planorbis magnificus and descrip- 
tions of two new forms of the same genus 
from the Southern States, Proc. U.S. Na- 
tional Mus. 33:697-800. 

BECK, H., 1837, Index molluscorum praesentis 
aevi musei principis augustissimi Christiani 
Frederici. Hafniae, 1-24. 



A CATALOGUE OF NEOTROPICAL PLANORBIDAE 



49 



BENTHEM JUTTING, V. S. S. van, 1943, Ueber 
eine Sammlung nichtmariner Mollusken aus 
dem niederschlagsarmen Gebiete Nordost- 
Brasiliens, Arch, Hydrobiol, Stuttgart. 39: 
458-489, . 

BEQUAERT, J. and W. J. CLENCH, 1939, The 
genus Plesiophysa. J. Conchol, 21:175-178. 

BIESE, W. A., 1951, Revision de los moluscos 
terestres y de agua dulce provistos de 
concha de Chile. Parte 4: Planorbidae. Bol. 
del Mus. Nac, de Hist. Nat. (Chile) 25:115- 
137. 

BONNET, M., 1846, Coquilles nouvelles ou peu 
connues, déscrites par M. Bonnet. Rev. et 
Mag. de Zool., 2è Sér., 16:279-282. 

BRODERIP, W. J., 1832, (Minutes of the meet- 
ing of 26 June 1832) Proc. Zool. Soc. , Lon- 
don, p. 125. 

BROWN, A. P. and H, A, Pilsbry, 1914, List 
of land and fresh- water mollusks of Antigua. 
Proc. Acad. Nat. Sei. Phila. 429-431. 

CARPENTER, P. P., 1857, Catalogue of the col- 
lection of Mazatlan shells in the British 
Museum. Brit, Mus., London, viii, 1-552. 
(The pages containing the description of 
Planorbis tuynens appeared in 1856). 

CHITTY, E,, 1853, Descriptions of thirty sup- 
posed new species and varieties of land and 
fluviatile shells of Jamaica, with observa- 
tions on some shells already described, 
Contrib, to Conchol. No. 1, 1-19. 

CLENCH, W. J, and C. G. AGUAYO, 1932, New 
Haitian mollusks. West Indian Mollusks 
No, 5. Proc. New England Zool. Club 13: 
35-38. 

, 1937, Notes and descriptions of 

some new land and freshwater mollusks from 
Hispaniola. Mem. Soc. Cubana Hist. Nat, 
ll(2):61-76, 

CLESSIN, S., 1878-1886, Plamrbis (in part). In 
Systematisches Conchylien- Cabinet of Mar- 
tini and Chemnitz, Ed, 2, Vol, l.Pt. 17; p. 63- 
430 were published by Clessin, as a continu- 
ation of Bunker's work, q.v. 

COOPER, J. G., 1893, On land and freshwater 
mollusca of Lower California. No. 3. Proc. 
Calif. Acad. Sei. Ser. 2. 3:338-344. 

COUSIN, A., 1887, Faune malacologique de la 
république de l'Equateur. Bull. Soc. Zool, 
France 12:187-287. 

CROSSE, H., 1864, Description d'espèces nou- 
velles. J. Conchyl. 12:132-154. 

, 1875, Diagnosis Planorbis novi 

Antillarum incolae. J. Conchyl. 23:329. 

CROSSE, H. and P. FISCHER, 1879, Diagnosis 
molluscorum novorum Guatemalae et rei- 
publicae Mexicanae incolarum. J. Conchyl. 
27:341-343. 

DALL, W. H., 1905, Land and freshwater mol- 
lusks of Alaska and adjacent regions, Harri- 
man Alaska Expedition, Vol, 12, 171 p. 
Doubleday, N.Y. 



DROUET, H., 1859, Essai sur les mollusques 
terrestres et fluviátiles de la Guyane Fran- 
çais, Mém, Soc, Acad, de l'Aube 23:7-116, 
Pis. 1-4. 

DUNKER, G., 1848, Diagnoses specierumnovar- 
um generis Planorbis collectionis Cumin- 
gianae. Proc. Zool. Soc. London 16:40-43. 

, 1841-1850, Ptoworbes (in part). In 

Systematisches Conchylien- Cabinet of Mar- 
tini and Chemnitz, Ed. 2, Vol. 1, Pt. 17. 
Pages 1-62 and Plates 1-10 and 16 were pub- 
lished by Dunker. See Clessin. 

FERGUSON, F. F. AND C. GERHARDT, 1956, 
Sexual apparatus of selected planorbid snails 
of the Caribbean area of interest in schisto- 
somiasis. Bol. de la Ofic. San. Panameri- 
cana (Washington, D.C.) 41:336-345. 

FISCHER, P. and H.CROSSE, 1870-1902, Études 
sur les mollusques terrestres et fluviátiles 
du Mexique et du Guatemala, In Mission 
Scientifique au Mexique et dans l'Amérique 
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GERMAIN, L., 1921-1924, Catalogue of the 
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GOODRICH.C. andH. VAN DER SCHALIE, 1937, 
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GOULD, A. A,, 1844, Descriptions and notices 
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, 1855, New species of land and fresh- 

water shells from Western North America, 
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GUPPY, R. J. L., 1871, Notes on some new 
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31L 

HAAS, F., 1938, Neue Binnen- Mollusken aus 
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, 1939, Malacological notes. The 

South American species of Planorbula. Zool. 
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, 1955, The Percy Sladen Trust Ex- 

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HALDEMAN, S. S,, 1841-1845, A monograph of 
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HUBENDICK, В., 1955, Phylogeny in the Plan- 
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, 1955a, The Percy Sladen Trust Ex- 
pedition to Lake Titicaca in 1937. 18. The 
anatomy of the Gastropoda. Trans. Linn. 
Soc. London l(3):309-327. 



50 



H. W. HARRY 



HUPE, M. M., 1854, Mollusques. In Castel- 
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, 1956a, Australorbis nigricans as 

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A CATALOGUE OF NEOTROPICAL PLANORBIDAE 



51 



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fresh- water mollusca. Amer. J. Conchol. 2: 
8-11. 

WAGNER, J. A., 1827, Testacea fluviatilia quae 
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(contains Planorbis weinlandi, described by 
Pfleffer). 



52 H. W. HARRY 



Z US AMME N FASSUNG 

EIN KRITISCHES VERZEICHNIS DER NOMINELLEN GATTUNGEN UND 
ARTEN NEOTROPISCHER PLANORBIDAE 

Die Verbreitung der neotropischen Planorbidengattungen reicht nach Norden 
hin mit nur wenigen Arten bis in die südlichen Vereinigten Staaten von Nordamerika. 
Von den 11 nominellen Gattungen deren typische Arten aus den Tropen der neuen 
Welt stammen, werden hier nur 3 als gültig anerkannt: Taphius, Dre рано trema und 
Acrorbis. Eine weitere noch namenlose Grattung wurde zwar auch erkannt, bleibt 
aber vorderhand absichtlich unbenannt. Obwohl eine nearktische Оэ^Нищ, Helisoma, 
sich Zugebenermassen südwärts bis nach Zentralamerika hin erstreckt, muss 
jedoch betont werden, dass die Angaben über das Vorkommen anderer nearktischer 
oder paläarktischer Arten in den Neuweltstropen jeglicher anatomischer Beweise 
entbehren. Einige neotropische und afrikanische Gattungen sind zwar vermutlich 
identisch; da jedoch die erstem in jedem Fall den letzteren gegenüber Priorität 
zu haben scheinen, wird darauf nicht näher eingegangen. 

Der vorliegende Katalog stellt einen Versuch dar, sowohl den locus typicus 
wie auch die ursprünglichen diesbezüglichen Schriften sämtlicher jemals benannten 
planorbiden Arten aus der Neotropen zusammenzufassen. Von diesen Arten wurden 
207 in 21 "Arten- Gruppen" zusammengefasst, deren Mitglieder wohl synonym sein 
dürften. Weitere 32 Arten wurden unter incertae sedis angeführt; diese scheinen 
sich, zumindest teilweise, von den 21 Arten-Gruppen zu unterscheiden, können 
aber, mangels anatomischer Angaben, keiner Gattung mit Bestimmtheit zugeteilt 
werden. Schliesslich sind noch 11 nomina nuda sowie 4 extralimitale Arten ver- 
zeichnet. Das Schrifttum ist weitgehend angegeben. 



RESUME 

UN CATALOGUE CRITIQUE DES GENRES PLANORBES 
NÉOTROPICAUX NOMINAUX ET DE LEURS ESPÈCES 

Vers le nord, les genres planorbes néotropicaux ne pénètrent que par quelques 
espèces dans les régions méridionales des États Unis de l'Amérique du Nord. Des 
11 genres nominaux dont les espèces-types proviennent des tropiques du nouveau 
monde, seulement 3 sont considérés valides: Taphius, Drepanotrenia et Acrorbis. 
Un genre additionel, point nommé encore et laissé ici délibérément innommé, a 
été également reconnu. Quoique le genre néarctique Helisonia s'étend, sans aucun 
doute, jusqu'en Amérique Centrale, il n'enest pas de même pour les autres genres 
néarctiques ou paléarctiques dont la présence a été signalée dans les régions néo- 
tropicales et il faut souligner que ces rapports sont dépourvus de toute corrobora- 
tion anatomique. Remarquons aussi que certains genres néotropicaux et africains 
sont probablement identiques; mais, comme dans tous les cas connus les premiers 
semblent avoir precedence sur les derniers, la question n'a pas été approfondie. 

Ce catalogue représente un essai d'assembler les références originales, 
aussi bien que les localités-types, de toutes les espèces planorbides néotropicales 
nommées. De ces espèces, 207 ont été divisées en 21 "groupes d'espèces" dont 
les membres sont probablement synonymes; 32 autres espèces sont citées comme 
incertae sedis ; elles semblent, partiellement du moins, se différentier des 21 
groupes d'espèces, mais ne peuvent être assignées à aucun genre faute de détails 
anatomiques. Finalement sont cités 11 no>ni)m nuda et 4 espèces extralimitales. 
Une bibliographie étendue est donnée. 



A CATALOGUE OF NEOTROPICAL PLANORBIDAE 53 

RESEÑA 

UN CATALOGO CRITICO DE GENEROS NOMINALES Y DE ESPECIES DE 
PLANORBIDAE NEOTROPICALES 

Los géneros de Planorbidae Neotropicales tienen solamente unas pocas 
especies septentrionales en la región Sur de los Estados Unidos de Norte América. 
De los once géneros nominales que se basan en especies de tipos Neotropicales, 
solamente 3 son considerados válidos: Taphiiis, D re ()a>io trema, y Acrorbis. 
También se reconocen como válidos un género que se han dejado sin nombre 
deliberadamente. El género Neartico Helisoma se extiende tan al Sur como Centro 
América, mientras que la mención de otros géneros Nearticos y Palearticos que 
llegan de la reglón Neotropical no está confirmada por datos anatómicos. A 
pesar de que algunos géneros Neotropicales y Africanos son idénticos, el género 
Neotropical parece tener prioridad en todos los casos conocidos, aunque no se 
haya investigado extensamente la cuestión. 

Hemos tratado de mencionar referencias originales y localidades típicas de 
todas las especies nominales de los planorbidos de los Neotrópicos. Entre ellos, 
207 se clasifican en 21 "grupos-especies". Los miembros de cada grupo son 
sinónimos probablemente. Treintaidos especies están agrupadas enmcertae sedis. 
Algunas de estas parecen diferenciarse de los 21 grupos de especies, pero la falta 
de datos anatómicos no nos permite agruparlos en géneros. Once nomina mida y 
cuatro especies extra son mencionadas lo mismo que se proporciona una amplia 
bibliografía. 



КРИТОТЕСКИИ КАТАЛОГ ОПИСАННЫХ РОДОВ И ВИДОВ НЕОТРОПИЧЕСКИХ 

PLANORBIDAE 

Харольд В, Харри 



Резюме 

Роды нео тропических планорбид, распространенные вплоть 
до юга США, представлены небольшим числом видов. Из 11 опи- 
саннмх родов, типами которых являются неотропические виды, 
признаны самостоятельными только 3: Taphius, Drepatwtrema и 
Acrorbis. Кроме них имеется один еще не описанный род, на- 
звание для которого, однако, не предлагается и в этой работе, 
Неарктмческий род Helisoma распространен до крайнего юга Цен- 
тральной Америки; наличие других неарктических и палеаркти- 
ческих родов анатомическими исследованиями не подтвердилось. 
Хотя вопрос об идентичности неотропических и африканских род- 
ов нельзя считать полностью решенным, некоторые неотропические 
и африканские роды, вероятно, идентичны, однако, названия нео- 
тропических родов во всех случаях должны быть сохранены в силу 
приоритета, 

Сдела1на попытка привести оригинальные описания и данные о 
типовых местонахождениях всех описанных видов планорбид нео- 
тропической области. Имеющиеся в литературе 207 названий объ- 
единены в 21 „группу видов"; члены каждой такой группы являют- 
ся, вероятно, синонимами, 32 „вида" приходится рассматривать 
как виды неясного систематического положения. Некоторые из них, 
по-видимому, отличаются от „видов" объединенных в группы, но 
отсутствие анатомических данных не позволяет уточнить их родов- 
ую принадлежность. Перечислены также 11 nomina muía и Ц. вида, 
ошибочно указанные для области. Приведена подробная библиогра- 
фия. 



МА1АСОЮС1А, 1(1): 55-72 

CYTOTAXONOMIC STUDIES OF FRESHWATER LIMPETS 
(GASTROPODA: BASOMMATOPHORA) 

I. THE EUROPEAN LAKE LIMPET, ACROLOXUS LACUSTRIS^ 

by J. B. Burch^ 

ABSTRACT 

Acroloxus lacustris (Linnaeus) is a freshwater limpet common to Europe, 
northern Asia and Caucasia. It has nearly always been assigned to the basom- 
matophoran family Ancylidae, and hence is generally regarded as one of the most 
specialized and phylogenetically advanced basommatophorans. 

It is shown in this paper that in regard to certain details oí cytology, Л . 
lacustris should not be considered closely related to other Ancylidae, but rather 
placed in a family by itself, the Acroloxidae, a conclusion corroborated by other 
authors on morphological grounds. Indeed, the various cytological differences 
would tend to further separate Acroloxus from other Basommatophora. The dif- 
ferences observed consist in the large size of the various cells of spermatogenesis, 
the greater volume ratio of chromatin to cytoplasm, the relatively large size of the 
chromosomes and the morphology of the mature sperm, whose heads are long and 
thread-like, not bullet- or turnip- shaped like those found in other basommatophor - 
an snails. In addition, the chromosome number (n=18), although characteristic of 
the Basommatophora in general, is different from that found in other freshwater 
limpets (x or basic haploid number -15 in the Ancylinae-Ferrissiinae; n=17 in 
the Laevapecinae). 

The mitotic chromosomes of A. lacustris are metacentric as characteristic 
of all Basommatophora; 6 pairs (including the 2 largest and the smallest) are 
medianly constricted; the other 12 pairs are submedianly or subterminally con- 
stricted. This is the first time the caryotype of any Euthyneuran snail has been 
accurately determined and figured. 

The phylogenetic position of the Acroloxidae may be close to the base of the 
Basommatophora as suggested by Bondesen and Hubendick, but at the present state 
of knowledge the evidence which would tend to support such a conclusion can not be 
found in details of cytology. But, contrary to earlier views reached on purely ana- 
tomical grounds, the position of the Ancylidae, as determined by their chromosome 
numbers, should also be near the base of the Basommatophora, but not close to the 
Acroloxidae because of the other cytological differences. 



INTRODUCTION 

Acroloxus lacustris (Linnaeus) is a 
freshwater limpet common to Europe, 
northern Asia and Caucasia. It is often 
called the "lake limpet" because of its 
preference for a lentic environment in 
contrast to the other common freshwater 
limpet of its region, Ancylus fluviatilis 
Müller^, which inhabits rivers. 



•'•This investigation was supported (in part) by 
a research grant, 2E-41, from the National 
Institute of Allergy and Infectious Diseases, 
U. S. Public Health Service. 

2 Museum and Department of Zoology, Univer- 
sity of Michigan, Ann Arbor, Michigan, U.S.A. 



Most moUuscan systematists have 
placed AcroZoxMS in the basommatophoran 
family Ancylidae which originally contain- 
ed all freshwater limpets. However, Bon- 
deson (1950) and Burch (1961b) have con- 
tended that the differences found between 
Acroloxus and other ancylids in regard 
to egg- capsule morphology and spermato- 
genesis are great enough to warrant its 
separation as a distinct family. These 
authors were not the first to appreciate 



"^Generic designations given here are in accord 
with Opinion 363 of the International Commis- 
sion on Zoological Nomenclature (Hubendick, 
1952; Hemming, 1955). 



(55) 



56 



J. В. BURCH 






•^ ''ш: 















.7*«' 

■X 



>»v 




• "^ • » ^ v tie" 









10 



• * • 



Al 



mi 



FIGS. 1-5, Chromosomes oi Acroloxus lacustris. Figs. 1-3. Spermatogonia! metaphase chromo- 
somes. The chromosomes in Fig, 1 are excessively contracted. A camera lucida drawing of these 
chromosomes is shown in Fig. 16. The chromosomes in Figs. 2 and 3 have divided. Camera lucida 
drawings of Figs. 2 and 3 are shown in Figs. 18 and 24. Fig. 4. Late prophase I (diakinesis) 
chromosomes. Fig. 5. Metaphase I chromosomes. 

FIG. 6. Spermatogonial late prophase chromosomes of Rhodacmea cahawbensis. 

FIG. 7. Spermatogonial metaphase chromosomes of Laevapex fuscus. A camera lucida drawing 
of these chromosomes is shown in Fig, 17. 



CYTOTAXONOMY OF ACROLOXUS 



57 



the differences exhibited by Acroloxns, 
as indicated by Walker's (1923) precedent 
of placing it in a subfamily by itself 
among the Ancylidae. Most recently 
Hubendick (1962) has also argued for 
familial status ioT Acroloxns on morpho- 
logical grounds. 

Chromosome studies of freshwater lim- 
pets are rather sparse and to date are 
restricted to only six publications (Le 
Calvez and Certain, 1950; Burch 1959a, b, 
1960a, c; Burch, Basch and Bush, 1960). 
The present report presents cytological 
information obtained in our laboratory 
on the common European limpet, Acro- 
loxus lacustris, and discusses the signi- 
ficance of these findings in respect to 
commonly held concepts of systematics 
and phylogeny in freshwater limpet-like 
mollusks . 

Grateful acknowledgement is made to 
Dr. Dorothea Franzen, Illinois Wesleyan 
University, Bloomington, Illinois, U. S. A., 
and to Mr. Jack Hayworth, University of 
Reading, Reading, England, for supplying 
me with the cytological material of Acro- 
loxns lacustris. I am also indebted to 
Dr. Henry van der Schalle, Museum of 
Zoology, University of Michigan for faci- 
lities and many kindnesses, to Mrs. Eliz- 
abeth Poulson, also from our Museum, 
for technical assistance during part of 
the work, and to Mrs . Anne Gismann for 
critically reading the manuscript. 

MATERIALS AND METHODS 

Specimens used in this study were ob- 
tained by Dr. Dorothea Franzen and Mr. 
Jack Hayworth from two localities in 
England. The material examined con- 
sisted of ovotestes from 3 specimens 



taken along the River Thames at Sonning 
(near Reading) on April 13, 1959, and 
from 7 specimens collected near East 
Bergholt, Suffolk, on June 26, 1959. The 
tissues were killed, fixed and preserved 
in Newcomer's (1953) fluid and stainedby 
the acetic-orcein squash technique (La 
Cour, 1941) for chromosome studies, or 
stained with haematoxylin and eosin for 
a general histological study of gameto- 
genesis. Tissues for the latter study 
were washed in absolute alcohol, cleared 
in chloroform, embedded in paraffin and 
sectioned at 15 miera. Shells of dupli- 
cate specimens (from the Thames River 
at Sonning) have been deposited in the 
collection of the Museum of Zoology, Uni- 
versity of Michigan (UMMZ cat. no. 
207600). 

Observations were made with aTiyoda- 
microscope using a 90X (n.a. 1.25) oil 
immersion objective and 10-30X oculars. 
The chromosomes in Figs. 12-26 were 
drawn with the aid of a camera lucida 
and reproduced at a table top magnifica- 
tion of 4650X. Photographs (Figs. 1-11) 
were taken using a 20X ocular, oil im- 
mersion objective, a Kodak Wratten 57A 
(green) filter, and Kodak High Contrast 
Copy and Ektachrome Type F films. 



OBSERVATIONS 
1. Cytology of Acroloxns lacustris 
a. Sperm atogonial Divisions 

Thirty-six chromosomes are easily 
counted during metaphase of spermato- 
gonial divisions of Acroloxns lacnstris 
(Figs. 1-3, 16, 18, 24). Primary con- 
strictions can easily be observed in these 
metaphase chromosomes, and in addition 



FIG. 8-9. Chromosomes of Ancylus ßuviatilis. Fig. 8. Late Prophase I (diakinesis) chromo- 
somes. A camera lucida drawing of the chromosomes of a cell similar to this one is shown in 
Fig. 23. Fig. 9. Metaphase I chromosomes. A camera lucida drawing of these chromosomes is 
shown in Fig. 26. 



Metaphase I chromosomes of Rhodacmea cahawbensis . 

Metaphase I chromosomes of Laevapex fuscus . A camera lucida drawing of these 



FIG. 10 

FIG. 11 

chromosomes is shown in Fig. 22 

Figures 1-11 X1470. 



58 



J. В. BURCH 



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12 ^ 13 




<^ 7 ^ 



17 



16 



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C3r 



19 



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20 ^ ♦ 






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21 






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15 



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CYTOTAXONOMY OF ACROLOXUS 



59 



to their constrictions they are often also 
very noticeable because they are non- 
staining or only lightly staining (Fig. 1; 
the non- staining character associatedwith 
the primary constrictions is not shown 
in Fig. 16, and only in the shaded chro- 
mosomes in Fig. 12). 

During their period of maximum con- 
traction, spermatogonial metaphase chro- 
mosomes appear to be divided into 6 
pairs of medianly or nearly medianly 
constricted homologues (shaded in Figs. 
12-14) and 12 pairs of distinctly sub- 
medianly or subterminally constricted 
homologues (solid in Figs. 12-14). The 
two largest pairs and the smallest pair 
of chromosomes are medianly constricted. 
One pair of chromosomes has secondary 
constrictions (the 10th pair shown in Fig. 
12). 

There is considerable variation in the 
degree of contraction of spermatogonial 
metaphase chromosomes. The extent of 
this variability can readily be observed 
in Figs. 1-3, 12-14, 16, 18, 24. Mea- 
surements in miera for the homologous 
pairs of excessively contracted chromo- 
somes shown in Fig. 1 are as follows 
(arranged in decreasing order, see also 
Fig. 12): 4.7, 4.1, 3.4, 3.1, 3.0, 3.0, 2.9, 



2.8, 2.7, 2.7, 2.7, 2.5, 2.5, 2.5, 2.5, 2.3, 
2.2, 1.9. Similar highly contracted chro- 
mosomes have been found in other spe- 
cies of basommatophoran snails and have 
been discussed by Burch (1960a). 

b. Meiotic Divisions 

Eighteen bivalents can be readily ob- 
served during late prophase (diakinesis) 
and metaphase of the first meiotic di- 
visions of spermatogenesis. The pairing 
behavior of the bivalents appeared to be 
normal, and during diakinesis the paired 
chromosomes were held together by one 
or more chiasmata. Details of the chro- 
mosome cycle of Acroloxiis laciistris 
during meiosis appear to be similar in 
most respects to that of other basomma- 
tophoran snails as described by Burch 
(1960c). 

с Mature Sperm 

The mature sperm of Acroloxiis laciis- 
tris were first described by Retzius 
(1906) and the present observations do 
not add additional information but merely 
confirm his report. The mature sperm 
as seen in the ovotestis occur in large 
bundles of many spermatozoa each. The 
head segment or nucleus is extremely 



FIGS. 12-14. Chromosomes of three spermatogonial cells oi Acroloxus laciistris. The chromo- 
somes are paired and arranged according to decreasing lengths. Medianly constricted chromo- 
somes are shaded. Fig. 12. Aligned chromosomes of Figs, 1 and 16. Fig. 13. Aligned chromosomes 
of Figs. 2 and 18. Fig. 14. Aligned chromosomes of Figs. 3 and 24. 

FIG. 15. Aligned mitotic metaphase chromosomes of Laevapex fiiscus from Figs. 7 and 17. 

Camera lucida drawing of mitotic metaphase chromosomes of Acroloxus lacustris 



These chromosomes are shown paired and arranged according to decreasing 



FIG. 16 

shown in Fig. 1 

lengths in Fig. 12. 

FIG. 17. Camera lucida drawing of mitotic metaphase chromosomes of Laevapex fus cus shown 
in Fig. 7. These chromosomes are shown paired and arranged according to decreasing lengths in 
Fig. 15. 

FIG. 18. Camera lucida drawing of mitotic metaphase chromosomes of Acroloxus lacustris 
shown in Fig. 2. These chromosomes are shown paired and arranged according to decreasing 
lengths in Fig. 13. 

FIG. 19. Camera lucida drawing of late mitotic prophase chromosomes oi Ancylus fluviatilis. 

FIGS. 20-21. Camera lucida drawing of chromosomes of meiosis I of Ferrissia parallela. Fig. 
20. Metaphase I. Fig. 21. Late Prophase I (diakinesis). 

FIG. 22. Camera lucida drawing of Metaphase I chromosomes of Lae^ya/^eAr/MscMS shown in Fig, 11. 

FIG. 23. Camera lucida drawing of Prophase I (diakinesis) chromosomes of Ancylus fluviatilis. 
A photograph of the chromosomes of a cell similar to this one is shown in Fig, 8. 

Figures 12-23 X1940. 



60 



J. в. BURCH 



long and thin (thread-like), and, in acetic- 
orcein squash preparations, can hardly 
be distinguished from the sperm tail seg- 
ment. The contrast of this sperm mor- 
phology to that of other basommatophoran 
snails will be discussed below. 

2. Comparisons with Ancylids and 
other Basommatophora. 

After looking at many basommatophoran 
species, representing many groups, I 
have been struck by the general uniform- 
ity of various details of spermatogenesis. 
This includes the general appearance of 
the cells at the various stages, the vol- 
ume ratio of the nuclear material to the 
cytoplasm, the general size of the chro- 
mosomes, and the appearance of the 
sperm. In Acroloxus lacustris, I was 
surprised to find that these various de- 
tails were strikingly different. 

a. Spermatogonial Chromosomes 

All of the cells of spermatogenesis 
are much larger than those observed in 
other basommatophoran snails, and the 
ratio of chromatin to cytoplasm is no- 
ticeably greater (although no actual quan- 
titative measurements were made) . 

The mitotic metaphase chromosomes 
observed during spermatogonial divisions 
are noticeably larger than any previously 
observed in Euthyneuran snails. Nor- 
mally contracted metaphase chromosomes 
during these divisions measure from 7.0 
miera for the largest chromosomes to 
3.5 miera for the smallest. Measure- 
ments for spermatogonial chromosomes 
in similar preparations for other fresh- 
water basommatophoran snails have been 
given as 3.7 miera for the largest and 
0.7 miera for the smallest (Burch, 1960a, 
c; Burch and Bush, 1960). Thus, in com- 
parative terms, the chromosomes of 
Acroloxus lacustris are approximately 
twice the size previously found for other 
species of the order. This size differ- 
ence can be readily observed, as regards 
the Ancylidae, by comparing the chromo- 
somes of A. Zací^síns (Figs. 1-3, 12-14, 
16, 18, 24; spermatogonial metaphase) 
with the corresponding chromosomes of 



the ancyline limpets, Rhodacmea cahaiv- 
bensis (Fig. 6; late spermatogonial pro- 
phase) and Ancyhis fluviatilis (Fig. 19; 
late spermatogonial prophase), and the 
laevapecine^ limpet Laevapex fusciis 
(Figs. 7, 15, 17, 25; spermatogonial meta- 
phase) . 

In comparing the chromosome number 
of Acroloxus lacustris (n=18, 2n=36) with 
those known from other freshwater lim- 
pets (Table I), it is readily apparent that 
this number, although characteristic of 
the Basommatophora in general, has not 
yet been observed in other freshwater 
limpets. The numbers n=15, 30 and 60 
(x=15) have been reported for the Ancy- 
linae and Ferissiinae (Burch, Basch and 
Bush, 1960) and the number n-17 for the 
Laevapecinae^ (Burch, 1960a, c) (see 
Table I). 

When the caryotype oi Acroloxus lacus- 
tris (Figs. 12-14) is compared to that 
of Laevapex fuscus (Fig. 15), the most 
obvious difference between the two (other 
than sizes of the chromosomes and their 
number) is that the two largest pairs of 
chromosomes of Л, lacustris are medianly 
constricted, while the two largest pairs 
of L. fuscus are submedianly or subterm- 
inally constricted. It would be very in- 
teresting to compare the caryotypes of 
other species of freshwater limpets and 
to ascertain whether or not the above 
differences will prove to be significant. 

b. Meiotic Chromosomes 

The meiotic chromosomes of AcroZoxHS 
lacustris are considerably larger than 
those seen by me or reported by others 
for any other basommatophoran snail. 
These size differences, as compared to 
various ancylid limpets, are illustrated 
in Figs. 4, 5, 8-11, 20-23, 26. Late pro- 
phase I (diakinesis) chromosomes of A. 
lacustris are shown in Fig. 4. As can 
readily be seen, these are much larger 
than the chromosomes of the same stage 
of Ancylus fluviatilis (Figs. 8, 23) and 



In this paper the Laevapecinae are considered 
as a subfamily of the Ancylidae (see Footnote 
8 and Table I). 



CYTOTAXONOMY OF ACROLOXUS 61 

TABLE I: Chromosome Numbers In Freshwater Limpets^ 



Species 


n 


2n 


Source 


Acroloxidae 








Acroloxus la cus tri s 


18 


36 


England 


Ancylidae 






- 


Ancylinae 
Rhodacmea cahawbensis ^ 








15 


30 


Alabama, U. S. A. 


Ancyhis fluviatilis 


60 


ca.l20 


England 


Ferrissiinae 








Ferrissia parallela 


30 


60 


Michigan, U. S. A. 


Ferissia tarda 


30 


-- 


Michigan, U. S. A. 


Laevapecinae^ 








Laevapex fits cus 


17 


34 


Michigan, U. S. A. 




17 


34 


Virginia, U. S. A. 


Burnupia sp. 


17 


-- 


Republic of South Africa 



5 From Burch, 1960a, c, 1961a and this report; Burch, Basch and Bush, 1960. 

6 Rhodacmea is considered here to belong to the Ancylinae, s.S., because of similarities in shell, 
jaw, radula, and dorsal muscle scars. These and other comparative aspects will be discussed 
in greater detail in a later paper on systematics of freshwater limpets. 

"^ Hannibal (1912) created the subfamily Laevapecinae for Laevapex s. s. ,Fisherola а.т\а Walkerola. 
Gwatkin (1914), Pilsbry (1925) and Baker (1925) have shown that snails of the latter two taxo- 
nomic categories should be placed near or with the Lymnaeidae (Lancinae). Despite their 
divergent chromosome number, the Laevapecinae are provisionally left within the Ancylidae. 
Burnupia is herewith added to the Laevapecinae because of similarities to Laevapex in male 
reproductive structures, dorsal muscle scars and chromosome numbers. Anatomical details 
of Burnupia will be presented in a later paper. 



Ferrissia parallela {Fig. 21) . Metaphase 
I chromosomes of Acroloxus lacustris 
are shown in Fig. 5. These are corre- 
spondingly much larger than metaphase I 
chromosomes of Ancylus fluviatilis {Yigs. 
9, 26), Rhodacmea cahaivbensis (Fig. 10), 
Ferrissia parallela (Fig. 20) and Leava- 
pex fuscus (Figs. 11, 22). 

Because of their relatively larger size 
one might expect a higher chiasmata fre- 
quency for meiotic chromosomes in A. 
lacustris than in other Basommatophora. 
However, such a comparison was not at- 
tempted in this study. 

с Mature Sperm 

In the Basommatophora (with the ex- 
ception of Acroloxus) the sperm head is 
bullet- or turnip- shaped following fixa- 
tion in Newcomer's fluid and acetic-orcein 
staining. In Acroloxus lacustris the 
sperm head is strikingly different. It is 
a very fine thread of slight diameter and 
very long. Such sperm would at least 



superficially appear to be similar to those 
described by Tuzet (1950) for Aplysia 
and by Franzen (1955) for various opis- 
thobranchs (e.g., Acera, Cylicbm, Aplysia, 
Limapontia) . 

Retzius (1904) and later Franzen (1956) 
extensively studied spermiogenesis among 
invertebrates and both concluded that the 
various types of mature sperm could be 
generally placed into two groups, one of 
"primitive", the other of "modified" 
sperm. Franzen defines primitive sperm 
as follows: "The nucleus is short and 
of rounded or conical shape. Also the 
middle piece is short, and contains 4-5 
mitochondrial spheres arranged in a regu- 
lar ring around the axial filament. The 
tail is formed by a thin filament which 
issues from a centriole at the posterior 
part of the head, traverses the middle 
piece, and reaches a length of about 50 
miera. The terminal portion of the tail 
is formed by a set-off thinner portion, 
the end piece." Sperm deviating from 



62 



J. В. BURCH 







"Ъ 

<''^ 






25^ ' 



26 ^ 



FIG. 24. Camera lucida drawing of mitotic metaphase chromosomes of Acroloxus lacustris 

shown in Fig. 3. These chromosomes are shown paired and arranged according to decreasing 
lengths in Fig. 14. 

FIG. 25. Camera lucida drawing of mitotic prometaphase chromosomes of Laevapex fuscus. 

FIG. 26. Camera lucida drawing of metaphase I chromosomes of Ancylus ßuviatilis shown in 

Fig. 9. 

Figures 24-26 X1940. 



this type are considered modified. Pri- 
mitive sperm, although occuring in the 
Placophora (^Polyplacophora), Soleno- 
gastres (^Aplacophora), Pelecypoda, Sca- 
phopoda and Diotocardia, have not been 
found in Euthyneura. 

The sperm of Acroloxus lacustris are 
highly modified. The nucleus, instead of 
being short and round or conical, is very 
long, forming almost 1/4 the length of the 
spermatozoon. It is thread-like and hard- 
ly thicker than the tail piece. The acro- 
some can hardly be distinguished from 
the nucleus. 

The bullet- or turnip-shaped sperm 
nuclei of the other Basommatophora would 
at first sight appear much like that de- 
scribed above as primitive. However, 
Franzen (1955) considers them to also 
be highly modified without " . . .any trace 
whatsoever of primitive conditions in any 
of the forms." It is interesting to note 
that Franzen also reports sperm ap- 
proaching this second modification from 
some opisthobranchs (Actaeon, Onchi- 
doris, Partidida, Tritonia). 



Since the two modified sperm types 
found in the Basommatophora appear to 
be found also in the opisthobranchs, it 
might seem that the Basommatophora are 
really diphyletic, and that each group was 
derived independently from different opis- 
thobranch ancestors. According to Fran- 
zen (1956): *'If within a larger group a 
subgroup is found which has an entirely 
different type and genesis of the sperm 
unaccompanied by any essential differ- 
ences in the way of fertilization, and if 
the same type of sperm is found within 
another group the assumption is justified 
that the sperm possesses aphylogenetico- 
taxonomical significance." But after 
comparing the species he studied with 
current concepts of Euthyneuran phylogeny 
(e.g., Boettger, 1955) I was unable to 
correlate the recurrence of the two types 
of sperm with any consistency. It would 
seem therefore that the modified sperm 
of both orders arose independently; or, 
that the question of phylogeny and rela- 
tionships in Euthyneuran snails has not 
been finally settled. 



CYTOTAXONOMY OF ACROLOXUS 



63 



DISCUSSION 
1 . Systematics 

It seems desirable to present a brief 
historical account of systematics at the 
family level for freshwater limpets in 
general, since some present workers on 
these snails are either unaware of their 
classical groupings and of the changes 
subsequently made, or tend to ignore 
them. Moreover, since Acroloxus has 
nearly always been placed in the rather 
inclusive family Ancylidae, systematic 
considerations of that family also, in 
part, involve Acroloxus. 

In 1923 Bryant Walker, the leading 
authority on freshwater limpets, made 
the following observation concerning their 
taxonomy: "The classification of the 
Ancylidae is in a very unsatisfactory con- 
dition owing to the fact that . . . practi- 
cally nothing is known of the soft anatomy. 
The simple form of the shell not only 
renders the determination of the species 
exceedingly difficult, but affords very 
slight indications of generic relations, 
and none as to the evolutionary history 
and affinities of the various groups." 
Our state of knowledge concerning this 
perplexing group has advanced surpris- 
ingly little since that time. The ana- 
tomy of most freshwater limpets is still 
largely unknown. 

It has long been known that all fresh- 
water limpet-like mollusks should not be 
placed in the single family Ancylidae 
Rafinesque 1815 (see also Phylogeny p. 64). 
Some of the genera formerly includea 
have already been transferred to other 
families on well founded anatomical 
grounds. As early as 1882 Hutton desig- 
nated a separate family Latiidae for the 
New Zealand genus Latia because of the 
difference in position of its eyes, its 
peculiar radular teeth and lack of jaws. 
However, Hutton' s paper was overlooked 
by later authors. For example, Pelseneer 
(1901) and Walker (1923) both indicated 
that Latia should be put into a separate 
family, but neither actually made this 
change. Hannibal (1912) proposed the 
subfamily Latiinae, "n. sub-fam." and 



Thiele (1931) raised it to familial rank. 
Later, Boettger (1955) reduced Latiinae 
again to subfamilial rank, but within the 
Chilinidae. 

Gwatkin (1914) pointed out that in radu- 
lar characters and jaw the west Ameri- 
can Lanx resembled the Lymnaeidae. 
Pilsbry (1925) followed up this observation 
and raised Walker's (1917) subfamily 
Lancinae to family status. He noted that 
Lanx had "no direct or near relation to 
Ancylidae. It belongs to a separate fam- 
ily, related to the Lymnaeidae somewhat 
as the Ancylidae are to thePlanorbidae." 
H. B. Baker (1925) showed conclusively 
that anatomically Lanx was indeed a 
lymnaeid, but retained the family name 
Lancidae, because of its peculiar modi- 
fication of the palliai complex. Thiele 
(1931) again subordinated Lancinae to 
subfamilial rank, but within the Lym- 
naeidae. 

Pilsbry and Bequaert (1927) placed 
Protancylus (sole genus ofWalker's (1923) 
subfamily Protancylinae) with the Planor- 
bidae (Bulininae). Hubendick (1958) in- 
dependently concluded that this change 
was necessary. Zilch (1959) also con- 
sidered Protancylus as a piano rbid, but 
retained its subfamilial ranking. 

Bondesen (1950) proposed splitting off 
another limpet, Acroloxus , from the An- 
cylidae and placing it in its own family. 
In doing this he raised Thiele's (1931) 
subfamily Acroloxinae (^Ancylinae Wal- 
ker 1923) to the family Acroloxidae. The 
reason for this elevation in the syste- 
matic position of Acroloxus was its strik- 
ingly different egg- capsule morphology. 
There exist several other reasons for 
separating the dextral Acroloxus irom the 
sinistral Ancylidae (as understood here) 
and, more recently Zilch (1959), Burch 
(1961b) and Hubendick (1962) also con- 
sidered the Acroloxidae as a distinct 
family. 

The remaining taxa have generally been 
left with the Ancylidae or, if raised to 
familial rank, retained as closely associ- 
ated families. The elevation of certain 
groups to family status has not been uni- 
versally accepted, and the grounds for 



64 



J. В. BURCH 



these changes are usually not well found- 
ed? 

Hannibal (1914) raised his 1912 sub- 
family Laevapecinae to family rank. 
Wenz (1938) raised Hannibal's (1912) sub- 
family Neoplanorbinae and Walker's (1917) 
subfamily Ferrissiinae to family status, 
and also presumably Walker's (1923) An- 
cylastruminae to Ancylastridae. Boettger 
(1955) and Meyer (1955) also treated the 
Ferrissiinae as a separate family. Zilch 
(1959) recently raised Walker's (1917) 
subfamily Rhodacmeinae to familial rank. 

The descriptive cytological details and 
comparisons shown in this paper strength- 
en Bondesen's contention that Acroloxiis 
should be separated at the family level 
from other freshwater limpets. This 
has already been pointed out in a brief 
abstract by Burch (1961b). Their higher 
chromosome number (n=18) which differs 
from that of theAncylinae andFerissiinae 
(x=15), and Laevapecinae (n=17) is also 
considered as an additional cytological 
character speaking for separation. The 
divergent chromosome number of the 
Laevapecinae would suggest possible ba- 
sic differences from the Ancylinae also, 
which, if borne out by anatomical detail, 
might lead to their removal from the 
Ancylidae. As regards Acroloxiis, such 
a systematic separation as supported here 
seems justified also on more gross mor- 
phological grounds, since considerable 
differences in shell, radula and soft ana- 
tomy have been demonstrated between 
Acroloxiis and other freshwater limpets 
(e.g., see Walker, 1923; Hubendick, 1960, 
1962). 

2. Phylogeny 

For many years it has been known, or 
at least suspected, that the freshwater 
limpets are not monophyletic. For ex- 



"The Ancylidae are here considered to contain 
the following genera: Ancylastrum (Ancy- 
lastruminae); Ancylus, В ronde lia and Rhodac- 
mea (Ancylinae); Ferrissia, Gundlachia and 
Hebetancylus (Ferrissiinae); Anisancyliis , Bur- 
nupia, Laevapex and Uncancylus (Laevapecinae). 
This is a modification of Walker's (1923) clas- 
sification. 



ample. Walker (1923) stated: "The re- 
markable differences that have recently 
been discovered [by Gwatkin] in the rad- 
ulae of the various groups would certainly 
tend to strengthen the suggestions that 
have been made that the family [Ancyli- 
dae] as now recognized is not of homo- 
geneous origin, but of diverse ancestry, 
and that the similarity in conchological 
characters should be considered rather 
as an example of parallel development 
than as indicating a common line of de- 
scent." Although Walker was perhaps 
the first to state clearly such views on 
the polyphyletic origin of freshwater lim- 
pets, Hannibal (1914) was apparently ear- 
lier thinking along similar lines (although 
his groupings are largely unnatural ones). 

Phylogenetic considerations of fresh- 
water limpets go back many years, to 
Plate (1894), who considered Ancylus to 
be a tectibranch. Pelseneer (1901) took 
exception to this and placed Ancylus (A. 
fluviatilis + Acroloxiis lacustris) and 
Gundlachia near Planorbis with the Ba- 
sommatophora. His reasons for con- 
sidering Ancylus to be a basommatophor- 
an were: 1) the shape and position of 
its osphradium, 2) its palliai "gill", 3) 
its stomach with a pyloric caecum, 4) the 
position of the ventricle in relation to 
the auricle in its heart, 5) the separation 
of its male and female genital openings, 
and 6) its short second pedal commissure. 
He showed that Gundlachia was similar 
to Ancylus in its basic organization. 

In relation to other Basommatophora, 
Pelseneer considered Ancylus to be very 
specialized because of 1) its very concen- 
trated nervous system, 2) its acquisition 
of a secondary gill, 3) its loss of the 
lung, 4) the displacement of its heart, 
and 5) the early division of its herma- 
phroditic duct and the consequent great 
length of its oviduct. The position of the 
Ancylidae as now understood (and exclud- 
ing Л его /av/is), both in their relation to 
the Planorbidae and in regard to the 
other Basommatophora has not been chal- 
lenged by subsequent authors (e.g., see 
Hubendick, 1947; Meyer, 1955; Boettger, 
1955). 



CYTOTAXONOMY OF ACROLOXUS 



65 



Hubendick (1945) and others before him 
consider Chilinidae and Amphibolidae to 
be primitive Basommatophora. Since the 
more specialized Lymnaeidae appear to 
him (Hubendick, 1947) to be similar to 
these two families in type of tentacles 
and in having a muscle on the ventral 
side of the kidney, he considers the lym- 
naeids to be the most primitive of the 
" higher limnic Basommatophora" (-Bran- 
chiopulmonata) . In addition, he considers 
some lymnaeids^ and Chilùm to have simi- 
lar copulatory organs. 

Since among the '' Branchiopulmonata" 
the Ancylidae and the Planorbidae are 
most dissimilar to the Lymnaeidae, they 
appear to Hubendick to be the most spe- 
cialized. However, he points to certain 
similarities that the Ancylidae have with 
A))iphibola and СЫШга, i.e., the presence 
of an anal lobe, of lobate salivary glands, 
and of a flagellum (he considers the fla- 
gellum of Ancyhis to be histologically 
different from that of Amphibola: Chilina 
does not have a flagellum). The simi- 
larities of the salivary glands he con- 
siders unimportant. But the anal lobe 
he does not so easily dismiss. He (loc. 
cit.) says: "The homologization of An- 
cylus' lobe with one of those in Planor- 
bidae offers certain difficulties", and 
" as the shape of the lobe and the course 
of the rectum in the lobe agree well in 
Ancylidae with those in Thalassophila 
and Chilinidae, it might be possible for 
the lobe to be homologous with the anal 
lobe. . ." thereby indicating greater pri- 
mitiveness. But Hubendick continues to 
say that '* . . .if Ancylidae ought to be 
derived from any recent types of higher 
limnic Basommatophora" then " the justi- 
fication for this last argument disap- 
pears . . ."I 

At this point, the nature of the vari- 
ation of chromosome numbers in Euthy- 



9 He says that Lanx differs from other lymn- 
aeids in that it lacks a praeputium, but H. B. 
Baker(1925)in his excellent detailed treatment 
oi Lawc quite clearly describes the praeputium. 
I have also determined that Lanx has a well 
developed praeputium which seems to differ 
but little from that of other Lymnaeidae. 



neuran snails needs to be mentioned since 
they have phylogenetic significance. If 
one disregards erroneous and unreliable 
cytological reports (for discussion see 
Burch (1960c)) and considers chromosome 
numbers in the various Euthyneuran 
groups for which reliable information 
is available, in regard to their presumed 
morphological advancement, one immedi- 
ately sees that there is a gradual in- 
crease in chromosome numbers as one 
goes up the evolutionary scale. Haploid 
numbers of the marine "opisthobranchi- 
ate" snails are all less than 18 (Fig. 
27). The basic haploid number (x) for 
the freshwater Basommatophora is 18 
(Burch 1960c). The haploid numbers of 
nearly all members of the land-dwelling 
Stylommatophora are greater than 18. 
The increase in number is a gradual one 
as one goes from one closely related 
larger taxon to the next, indicating that 
change in chromosome number has re- 
sulted by aneuploidy rather than poly- 
ploidy. This was first pointed out for 
pulmonate snails by Husted and P. R. 
Burch (1946). In those families where 
polyploidy has been reported (Burch, 
1960b, d; Burch, Basch and Bush, I960) 
the diploid number basic to the group is 
readily discerned. The great constancy 
of chromosome numbers within large tax- 
onomic groups, especially in the lower 
Euthyneura, suggests that aneuploidy has 
been a rather rare occurrence, and that, 
when it occurs, it usually involves a 
whole major group, e.g., an order or 
family (sometimes only a genus in the 
Stylommatophora). Polyploidy is rare, 
and when it occurs it usually involves 
species (perhaps genera in the Ancylidae), 
and not larger groups. Also, chromo- 
some change by aneuploidy, when relat- 
ing to higher taxonomic categories seems 
to be by addition, rather than subtraction, 
of chromosomes. (For a more detailed 
discussion of the above concepts see 
Burch, 1961a; Burch and Heard, 1962). 

With the above information at hand it 
is then difficult to consider that the An- 
cylidae as here understood (x=15; n=17) 
are highly specialized derivatives of the 



66 



J. в. BURCH 



60 
36 
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Opisthobranchiata Basommatophora Sty lommatophora 

FIG. 27. ffistogram of haploid chromosome numbers reported in Euthyneuran snails.* Shaded 
areas show limits of variation, x refers to the basic haploid chromosome number. 



*From Beeson (1960, Nature, 186: 257), Burch 
(1960b, d; 1961a), Burch, Basch and Bush 
(I960), Burch and Heard (1962), Husted and 
Burch (1946; 1953, Virginia J. Scl., 4:62), 
Inaba (1953, J. Sei. Hiroshima Univ., 14: 221; 
1959, /b«i., 18: 71; 1959, Annot. Zool. Jap., 



32:81), Inaba and Hirota (1958, Jap, J. Zool., 
12: 157), Le Calvez and Certain (1950), Perrot 
(1930, Rev. Suisse Zool., 37: 397: 1938, Ibid., 
45: 487), Perrot and Perrot (1938, С Я Soc. 
Phys. Hist. nat. Geneve, 55: 92). 
**J. B. Burch, unpublished data. 



CYTOTAXONOMY OF ACROLOXUS 



67 



pulmonata" 



STYLOMMATOPHORA 
(n>18) 



BASO MMATOP HORA 



Branchiopulmonata 



Phys idae 
x=ir 



Lymnae idae 
x=l 



Aero loxidae 
n=l 




F lanorbidae 
x=18 



Ancy lidae 
x=15,17 



Archaeopu Imonat a 



EL Lobiidae 

x=18 

Amphibolidae • 
n=18 



'Ur -Basommatophora' 
x=18 . x=15,17 



Siphonariidae 
n=16 



"Opisthobranchiate" 
anees tors 

x=12,13,17 



FIG. 28. Possible relationships of various taxa within the subclass Euthyneura based (in part) on 
haploid chromosome numbers. For phy logenies based on various morphological considerations see 
Hubendick (1947) , Boettger (1955), Meyer (1955) and Morton (1955), 



Planorbidae (x=18) as contended by Pel- 
seneer (1901), but it would seem that 
they are perhaps much more primitive 
in nature. Brief attention has already 
been called to this possibility by the au- 
thor (Burch, Basch and Bush, 1960). 
Even tor Acroloxus , despite agreement in 
the chromosome numbers (n=18), there 
seems little justification in leaving its 
connections with the Planorbidae, when 
one considers the gross differences in 
other details of cytology, discussed previ- 
ously in this paper. 

Bondesen (1950), in considering the re- 
lationship of Acroloxus to other fresh- 
water pulmonates as shown by compara- 
tive egg capsule morphology, states that 



the origin of the Acroloxidae '* must be 
. . . sought nearer to more primitive 
forms within the Basommatophora." Hu- 
bendick (1962) most recently has advo- 
cated that Acroloxus had an origin in 
common with the primitive and aberrant 
Latia of New Zealand. He bases his con- 
clusions on what he considers similari- 
ties in the radulae and reproductive tracts 
of the two genera. However, Pelseneer 
(1901) who alone has studied the soft ana- 
tomy of Latia, pointed out certain im- 
portant dissimilarities between Latia and 
the ancylids (including Acroloxus lacus- 
tris, with which he was familiar) that 
cannot be overlooked. These differences 
include the morphology of the nervous 



68 



J. ß. BURCH 



system, the kidney, the lack of flagellum 
in Latia's male reproductive system (per- 
haps a superficial character), and the 
presence of a well-developed pulmonary 
cavity in Latia's Concerning the radula 
of Acroloxus Hubendick (loc. cit.) states 
that it " . . . has certain important simi- 
larities with that of Latia ." But, after 
carefully examining the radula of Latia, 
I find it very different irom Acroloxus 
and cannot understand Hubendick' s state- 
ment, unless he considers the arched 
rows of radular teeth of Latia and the 
semi-arched nature of those oi Acroloxus 
to be important. The only other author 
that I know of that has studied the radula 
of Latia is Hutton (1882), and his draw- 
ings also do not show the radular teeth 
of Latia to be similar to those reported 
by other authors for Acroloxus (e.g., 
see Walker, 1925). 

The aberrant spermatozoon of Acro- 
loxus lacustris has been considered an 
extreme specialization when compared 
with Lynnmea, Physa and Planorbarius 
(see Retzius, 1904; also Boettger, 1944). 
But if Bondesen's and Hubendick' s sug- 
gestions are correct in that Acroloxus 
had its origin near to primitive forms 
within the Basommatophora, and if it 
might be assumed that such a starting 
point could be from a group more pri- 
mitive than those so far studied in re- 
spect to spermiogenesis, then perhaps 
the anomalous sperm morphology might 
not by in the direction of extreme spe- 
cialization, but more closely like that of 
less specialized living groups not yet 
thoroughly investigated. Or perhaps the 
aberrant sperm are related to more spe- 
cialized species of a group less special- 
ized or more primitive than the Basom- 
matophora (i.e., an " opisthobranch" 
group) . 

That a critical réévaluation of phylo- 
geny and phylogenetically significant char- 
acters in the so-called "higher limnic 
Basommatophora" or " Branchiopulmon- 
ata", indeed, in the entire Euthyneura, 
is badly needed is readily apparent. But 
such a réévaluation of relationships must 
await the proper accumulation of detailed 



morphological data, which at present is 
unavailable for many Euthyneuran groups. 
Relationships of freshwater limpets to 
other Euthyneura as suggested by their 
chromosome numbers might be illustrated 
as in Fig. 28. 

LITERATURE CITED 

BAKER, H. В., 1925, Anatomy of Lanx, a limpet- 
like lymnaeid mollusk. Proc. Calif. Acad, 
of Sei. (Fourth Series), 14(8): 143-169, pis. 
11-14. 

BOETTGER, C. R., 1944, Basommatophora, In: 
Grimpe und Wagler: Tierwelt der Nord- 
und Ostsee. Liet 35, Teil ЭЬ'г : 242-478. 

, 1955, Die Systematik der euthy- 

neuren Schnecken. Verhandl. Deutsch. Zool. 
Ges. Tubingen, 1954: 253-280. 

BONDESEN, P., 1950, A comparative morpho- 
logical-biological analysis of the egg cap- 
sules of freshwater pulmonate Gastropods. 
Natura Jutlandica, 3: 1-208, pis. 1-9. 

BURCH, J. В., 1959a, Chromosomes of aquatic 
pulmonate snails (Basommatophora). Amer, 
Malacol. Union Ann. Reps. 1958, 25: 9-10. 

, 1959b, Chromosomes of aquatic 

pulmonate snails (Basommatophora), Dis- 
sert. Abstr., 20(4):1487-1488, 

, 1960a, Chromosome morphology of 



aquatic pulmonate snails (Mollusca: Gastro- 
poda). Trans. Amer. Microsc, Soc, ,79(4): 
451-461, 
, 1960b, Chromosomes of Gyraulus 



circumstriatus , a freshwater snail. Nature, 
186(4723): 497-498. 
, 1960c, Chromosome studies of 



aquatic pulmonate snails. Nucleus, 3(2): 
177-208. 
, 1960d, Chromosome numbers of 



schistosome vector snails. Z. Tropenmed. 
Parasit., 11(4): 449-452. 
, 1961a, The chromosomes of Plan- 



orbarius corneus (Linnaeus), with a discus- 
sion on the value of chromosome numbers in 
snail systematics. Basteria, 25(4/5): 45-52. 
, 1961b, Some cytological aspects of 



Acroloxus lacustris (Linnaeus), with a dis- 
cussion of systematics in fresh-water lim- 
pets. Amer. Malacol. Union Ann. Reps. 
1961, 28: 15-16. 

BURCH, J. B.,BASCH, P. F. and BUSH, L. L., 
1960, Chromosome numbers in ancylid 
snails. Rev, Portuguesa Zool. Biol. Ger. , 
2(3/4): 199-204. 

BURCH, J. B. and BUSH, L, L, , 1960, Chromo- 
somes oi Physa gyrina ?>a.y (Mollusca: Pul- 
monata). J. Conchy 1., 100: 49-54. 

BURCH, J, B. and HEARD, W. H. 1962, Chromo- 
some numbers of two species of Vallonia. 
(Mollusca: Stylommatophora: Orthurethra), 
Acta Biol, Acad, Sei. Hung., 12(1): 305-312. 



CYTOTAXONOMY OF ACROLOXUS 



69 



FRANZEN, A., 1955, Comparative morphologi- 
cal investigations into spermiogenesis among 
Mollusca. Zool. Bidrag Uppsala, 30: 399- 
456, pis. 1,2. 

, 1956, On spermiogenesis, morphol- 
ogy of the spermatozoon, and biology of 
fertilization among invertebrates. Ibid., 31: 
355-482, pis. 1-6. 

GWATKIN, H. M., 1914, Some moUuscan radu- 
lae. J. Conchol., 14(5): 139-148. 

HANNIBAL, H., 1912, A synopsis of the recent 
and tertiary freshwater Mollusca of the 
Calif ornian Province, based upon an onto- 
genetic classification. Proc. Malacol. Soc. 
Lond., 10: 112-211. 

, 1914, Note on the classification of 

the Ancylidae. Nautilus, 28(2): 23-24. 

HEMMING, F. (Ed.), 1955, Opinion 363. Desig- 
nation, under the plenary powers, of a type 
species in harmony with accustomed usage 
for the nominal genus "Ancylus" Müller 
(О. F.), 1774 (Class Gastropoda). Opinions 
and Declarations Rendered by the Interna- 
tional Commission on Zoological Nomencla- 
ture, 11(12): 185-202. 

HUBENDICK, В., 1945, Phylogenie und Tier- 
geographie der Siphonariidae. Zur Kenntnis 
der Phylogenie in der Ordnung Basomma- 
tophora und des Ursprungs der Pulmona- 
tengruppe. Zool. Bidrag Uppsala, 24: 1-216. 

, 1947, Phylogenetic relations be- 
tween the higher limnic Basommatophora. 
Ibid., 25: 141-164. 

, 1952, Proposed use of the plenary 



powers to designate a type species for the 
genus "Ancylus" Müller, 1774 (Class Gas- 
tropoda) in harmony with established nomen- 
clatorial practice. Bull. Zool. Nomencl. , 
6(8): 227-230. 
, (1958, A note on Protancylus P. and 



F. Sarasin. Beaufortia, 78: 243-250. 
, 1960, The Ancylidae of Lake Ochrid 



and their bearing on intralacustrine specia- 

tion. Proc. Zool. Soc. Lond., 133(4): 497-529. 

, 1962, Studies on Acroloxus (Moll. 



Basomm.). Göteborgs Kungl. Vetenskaps- 
och Vitterhets-Samhälles Handlingar. Sjätte 
Följden. Ser. В. 9(2): 1-68. 

HUSTED, L. and BURCH, P. R., 1946, The 
chromosomes of polygyrid snail's. Amer. 
Nat., 80: 410-429. 

HUTTON, F. W., 1882, Notes on some pulmonate 
Mollusca. Trans. New Zealand Inst. 1881. 
14: 150-158, pis. 3 and 4. 

LA COUR, L., 1941, Acetic-orcein: Anew stain- 
fixative for chromosomes. Stain Techn. , 16: 
169-174. 

LE CALVEZ, J. and CERTAIN, P. , 1950, Données 



caryologiques sur quelques Pulmones ba- 
sommatophores. С. R Acad. Sei., Paris, 
231(16): 794-795. 

MEYER, К. О., 1955, Naturgeschichte der 
Strandschnecke Ovatella myosotis (Drapar- 
naud). 

MORTON, J. E., 1955, The evolution of the El- 
lobiidae with a discussion on the origin of 
the Pulmonata. Proc. Zool. Soc. Lond., 125 
(1): 127-168. 

NEWCOMER, E. H., 1953, A new cytological and 
histological fixing fluid. Science, 118(3058): 
161. 

PELSENEER, P., 1901, Études sur des Gastro- 
podes pulmones. Mem. Acad. Roy. Sei., 
Lettr. Beaux- arts Belg., 54: 1-76, pis. 1-14. 

PILSBRY, H. A., 1925, The family Lancidae 
distinguished from the Ancylidae. Nautilus, 
38(3): 73-75. 

PILSBRY, H. A. and BEQUAERT, J., 1927, The 
aquatic mollusks of the Belgian Congo, with 
a geographical and ecological account of 
Congo malacology. Bull. Amer. Mus. Nat. 
Hist., 53(2): 69-602. 

PLATE, L., 1894, Studien über opistopneumone 
Lungenschnecken. II. Die Oncidiiden. Ein 
Beitrag sur Stammesgeschichte der Pul- 
monaten. Zool. Jahrb., Anat, , 7: 93-234. 

RAFINESQUE, C. S., 1815, Analyse de la Na- 
ture, ou Tableau de l'Univers et des Corps 
Organisés. Palerme. p. 136-149. 

RETZIUS, G., 1904, Zur Kenntnis der Spermien 
der Evertebraten. Biol. Untersuch., N. F., 
11(1): 1-32, pis. 1-13. 

, 1906, Die Spermien der Gastro- 
poden. Ibid., 13(1): 1-36, pis. 1-12. 

THIELE, J. , 1931, Handbuch der systematischen 
Weichtierkunde. Jena 1929-35. 2: 377-778. 

TUZET, O. , 1950, Le spermatozoïde dans la 
série animale. Rev. Suisse Zool., 57(10): 
433-451. 

WALKER, В., 1917, Revision of the classifica- 
tion of the North American patelliform 
Ancylidae, with descriptions of new species. 
Nautilus, 31(1): 1-10, pis. 1-3. 

, 1923, The Ancylidae of South Africa. 

London: Printed for the Author. P. 82. 
, 1925, New species of North Ameri- 



can Ancylidae and Lancidae. Univ. Mich., 
Occ. Papers Museum Zool., No. 165: 1-13. 

WENZ, W., 1938, Gastropoda. 1. Allgemeiner 
Teil und Prosobranchia. In: Schinde wolf, 
Handbuch der Paläozoologie. Lief. 1, 6:1- 
960. Borntraeger, Berlin. 

ZILCH, A., 1959, Gastropoda. 2. Euthyneura. 
In: Schindewolf, Handbuch der Paläozoolo- 
gie. Lief. 1, 6: 1-701. Borntraeger, Berlin. 



70 J. В. BURCH 

ZUSAMMENFASSUNG 

ZYTOTAXONOMISCHE STUDIEN ÜBER DIE NAPFSCHNECKEN 

DES SÜSS WASSERS (GASTROPODA: BASOMMATOPHORA). I. DIE 

EUROPÄISCHE BINNENSEENAPFSCHNECKE ACROLOXUS LACUSTRIS. 

Acroloxus lacustris (Linnaeus) ist eine in Europa, Nordasien und Kaukasien 
verbreitete Napfaschnecke die gewöhnlich der Basommatophorenfamilie Ancylidae 
zugerechnet wird und daher auch zu den spezialisiertesten und phylogenetisch am 
weitesten fortgeschrittenen Basommatophoren. 

Es wird hier gezeigt, dass in Anbetracht gewisser Einzelheiten des Zellbaues, 
A. lacustris nicht als eine den anderen Ancyliden verwandte Schnecke angesehen 
werden sollte, sondern eher in eine Familie für sich (Acroloxidae)gestellt werden 
sollte, wie es ja auch bereits von anderen Autoren aus morphologischen Gründen 
befürwortet wurde. Ja darüber hinaus scheinen die beobachteten zytologischen 
Unterschiede sogar für einen weiteren Abstand von den übrigen Basommatophoren 
zu sprechen. Diese Unterschiede bestehen aus der beträchtlicheren Grösse der 
verschiedenen spermatogenetischen Zellen , aus deren im Verhältnis zum Zyto- 
plasma grösserer Chromatinmasse, aus den verhältnismässig grossen Ausmassen 
der Chromosome und aus der Gestalt der Spermatozoen, deren Köpfe lang und 
fadenförmig und nicht geschoss- oder rübenförmig sind wie die der anderen Basom- 
matophoren. Ausserdem ist die Chromosomenzahl (n=18) des Acroloxus , obwohl 
für die Basommatophoren kennzeichnend, von der der anderen Napfschnecken des 
Süsswassers verschieden; die haploide Grundzahl ix) beträgt in den Ancylinae 
und den Ferrissiinae 15, während die in den Laevapecinae n=17 beträgt. 

Wie für sämtliche Basommatophoren charakteristisch, sind die mitotischen 
Chromosome des Acroloxus lacustris metazentrisch. Sechs Paare, darunter die 2 
grössten und das kleinste, sind median, die übrigen 12 submedian oder subzentral 
abgeschnürt. Es wurde hier zum ersten Male die Kariotype einer euthyneuren 
Schnecke genau festgestellt und abgebildet. 

Es könnte wohl sein dass die Acroloxidae, wie es schon Bondeson und Huben- 
dick vertraten, phylogenetisch in die Nähe der Wurzel des Basommatophoren- 
stammes zu stellen wären, doch kann die Zytologie, zumindestens beim heutigen 
Stand unseres Wissens, noch nicht das Beweismaterial für einen derartigen 
Schluss liefern. 

Auf Grund ihrer Chromosomenzahl wären auch die Ancylidae, im Gegensatz 
zur üblichen, auf rein anatomischer Grundlage geschlossenen Folgerung, ebenfalls 
in die Nähe der Wurzel der Basommatophoren zu versetzen, jedoch in Hinblick auf 
die anderen zytologischen Unterschiede, nicht in die unmittelbare Nähe der 
Acroloxidae. 



RESUME 

ETUDES CYTOTAXONOMIQUES SUR LES PATELUENS D'EAU DOUCE 
(GASTROPODA: BASOMMATOPHORA) I. LA PATELLE 
LACUSTRE EUROPÉENNE ACROLOXUS LACUSTRIS. 

L'Acroloxus lacustris (Linné) est une patelle lacustre répandue en Europe, en 
Asie septentrionale et en Caucasie, qui a généralement été rangée dans la famille 
basommatophore des ancylides et, par là, parmi les basommatophores les plus 
spécialisés et les plus avancés phylogénétlquement. 

Nous montrerons dans cet exposé que, en vue de certains détails cytologiques, 
A. lacustris ne saurait être placé dans le voisinage immédiat des ancylides, mais 
plutôt dans une famille séparée, les Acroloxidae, conclusion qui d'ailleurs se trouve 
aussi corroborée par d'autres auteurs pour raisons morphologiques. Plus que cela, 
les différences cytologiques observées semblent même indiquer un certain écart 
entre Acroloxus et les autres basommatophores. Ces différences se trouvent dans 
la grandeur des cellules de la Spermatogenese, dans le volume supérieur de leur 
chromatine par rapport au cytoplasme, dans les dimensions relativement grandes 
des chromosomes et dans la morphologie des spermatozoïdes mûrs, dont les têtes 



CYTOTAXONOMY OF ACROLOXUS 71 

sont longues et ñliformes, ne montrant point la forme de balle ou de navet ren- 
contrée chez les autres basommatophores. En outre, son nombre de chromosomes 
(n=18), quoique caractéristique pour les basommatophores en général, diffère de 
celui des autres patelles d'eau douce, dont le nombre haploïde fondamental de 
chromosomes (x) est ISpour les Ancylinaeet Ferrissiinae, pendant que n, le nombre 
haploïde, est 17 pour les Laevapecinae. 

Les chromosomes mitotiques de A. lacustris sont métacentrlques de façon 
caractéristique pour tous les basommatophores. Les constrictions sont médianes 
dans 6 paires, comprenant les 2 plus grandes ainsi que laplus petite, et submédianes 
ou subterminales dans les autres 12. C'est d'ailleurs la première fois que le cary- 
otype d'un mollusque euthyneure ait été minutieusement observé et figuré. 

Il se pourrait que la position phylogénétique des Acroloxidae serait à chercher 
plutôt près de la base du tronc basommatophore comme l'ont suggéré Bondesen et 
Hubendick, mais, à l'état actuel de nos connaissances, la cytologie ne peut pas 
encore fournir les preuves d'une pareille conclusion. 

Quant à la position des Ancylidae, elle se trouverait, contrairement aux con- 
clusions antérieures basées sur une évaluation purement anatomique, également 
proche de la base de l'arbre phylogénétique basommatophore relativement à leur 
nombre de chromosomes, mais pas en proximité immédiate des Acroloxidae à 
cause des autres différences cytologiques. 



RESEÑA 

ESTUDIOS CITOTAXONOMICOS SOBRE LAS LAPAS 
DE AGUA DULCE (GASTROPODA: BASOMMATOPHORA) I. LA LAPA 
DE LAGO EUROPEO, ACROLOXUS LACUSTRIS. 

El Acroloxus lacustris (Linnaeus) es una lapita de agua dulce común en Europa, 
norte de Asia y Caucasia. Casi siempre ha sido asignada a la familia basommato- 
phora Ancylidae, considerada como una de las más especiales y filogenéticamente 
avanzadas. 

Se demuestra en este estudio que en base a ciertos detalles de citología A. 
lacustris no debería considerarse muy relacionada a otros Ancylidae sino más 
bien como constituyendo una familia por sí sola, Acroloxidae , conclusión que ha 
sido corroborada por otros autores, en base de conocimientos morfológicos. 
Ciertamente las varias diferencias citológicas tienden a separar más los Acroloxus 
de los otros Basommatophora. Las diferencias observadas las constituyen el 
tamaño y mayor volumen de las varias células espermatogénlcas, el mayor 
volumen de cromatina en relación al citoplasma, la relativa mayor medida de los 
cromosomas y la morfología de la esperma madura cuyas cabezas son largas y en 
forma de bala o de nabo como se encuentran en los otros caracoles basommato- 
foros. En suma, el número de cromosomas (n=18), aunque característico de los 
Basommatophora en general, es diferente del que se encuentra en otras lapas de 
agua dulce (x o numero básico=J.5 en Ancylinae-Ferrissiinae;n=n en Laevapecinae). 

Los cromosomas mitóticos del A. lacustris son metacéntricos como es 
característico de todos los Basommatophora; 6 pares (incluyendo las 2 más 
grandes y las más pequeñas) que están medianamente ligados. Los otros 12 pares 
son submedianamente o subterminalmente ligados. Esta es la primera vez que el 

La posición filogenetica de los Acroloxidae puede que este muy cerca de los 
Basommatophora como sugerid Bondesen y Hubendick- Desafortunadamente al 
presente estado de conocimiento la evidencia que ayudaría a sostener tal conclu- 
sión no puede encontrarse en detalles de citología. Pero al contrario de opiniones 
antiguas alcanzadas en base a puros conocimientos anatómicos, la posición de los 
Ancylidae determinada por el número de cromosomas debería también estar muy 
cerca de los Basommatophora, aunque no cerca a los Acroloxidae debido a las 
otras diferencias citológicas. 



72 ЦИТОТАКСОНОШЯ РОДА АКРОЛОКСУС 

Иван Б. Бёрч 
АБСТРАКТ 

Acroloxus lascHstris (L.) пресноводный щитовидный мол- 
люск распространен в Европе, Азии и на Кавказе. Его всегда 
относили к басомматофорному семейству Ансиллидэ и поэтому 
он считался одним из наиболее специализированных и филогене- 
тически наиболее развитым видом из басомматофора. 

В этой работе показано, что в некоторых деталях цитоло- 
гии А. lacustris не должен считаться близким к другим ви- 
дам Ancylidae, но скорее он должен быть выделен в особое 
семейство - Acrol oxidas ; к тому же заключению пришли и 
другие авторы на основании морфологических данных. Цитоло- 
гические различия указывают даже на дальнейшее выделение 
рода Акролоксус из Басомматофора. Замеченные различия сос- 
тоят из гораздо большего размера разных сперматогенетических 
клеточек, пропорционально большего количества хроматина чем 
цитоплазмы, в сравнительно более крупных хромосомах, 
а также и в морфологии зрелой спермы, головка ко- 
торой длинна и нитевидна, а не ввиде пули или луковицы, 
как это наблюдается в других улитках среди Басомматофора. 
Кроме того, число хромосом (n=l8), хотя и характерно для 
Басомматофора вообще, отличается от обычного в других прес- 
новодных щитовидных моллюсков (х или основное хаплоидное 
число = 15 в Ancyllnae - Ferrissiinae ; п- 17 g Laevapecinae) . 

Митотические хромосомы А. lacustris метацентричны, что 
характерно для всех видов Басомматофора; 6 пар (включая 2 
наибольшие и наименьшие) сужены посредине; другие 12 пар 
сужены подальше от середины. Тут в первый раз кариотип какой 
либо улитки из всех видов Euthyneure точно определен и 
иллюстрирован . 

Филогенетическое положение Acroloxidae может быть в 
основе Басомматофора, как полагали Бондэсэн и Хюбэндик, но 
в настоящее время доказательств, подтверждающих такое заклю- • 
чение, в деталях цитологии не найдено. Но, вопреки ранее 
сложившемуся мнению, основанному на чисто анатомических дан- 
ных, систематгтческое положение Ancylidae , как это доказано 
числом их хромосом, должно быть в основе Басомматофора, но 
никак не рядом с Acroloxidae по причине других цитологи- 
ческих различий. 



MALACOLOGIA, 1962, 1(1): 73-114 

CONTRIBUTIONS TO THE MORPHOLOGY OF BU LINUS TROPICUS 
(GASTROPODA: BASOMMATOPHORA: PLANORBIDAE) 

By 

Ina Stiglingh, J. A. van Eeden and P. A. J. Ryke 

Institute for Zoological Research, 

Potchefstroom University for Christian Higher Education, 

Potchefstroom, Republic of South Africa. 

ABSTRACT 

A study was made on Bulmus (Bulinus) tropicus (Krauss), an African fresh 
water snail that is closely related to the intermediate hosts of the schistosomes of 
the hae»iatobiia)¡ group and which is also of veterinary importance as a carrier of 
the trematodes Paramphistomiim and Cotylophoron. Special attention was paid to 
three important taxonomic characters, the shell, radula and penial complex but the 
other systems were also examined both morphologically and histologically. 

The snail samples were selected both on the basis of their resemblance to 
typical specimens of B. tropicus and their geographical distribution in the region of 
the type locality. In spite of these precautions in the selection, the present study 
of the shell once more emphasizes the notorious polymorphism of the species. The 
important role of ecological factors in producing widely divergent shell types, 
differing in both shape and texture, is discussed. Although two main adult types oc- 
curred in our material, an elongated, narrowly umbilicate form associated with run- 
ning water, and a squat, widely umbilicate form associated with pools (ñg, 3), there 
was only one main type of juvenile, suggesting, as was observed by Schutte and van 
Eeden (1959a) for BiompMlaria /)/е(/Уегг, that the form of the juvenile is less affected 
by the environment than is the case in the adults. This seems logical as the latter 
have been exposed to the modifying influences for a longer period than the younger 
snails. A conchometrical analysis was undertaken and the length, breath, aperture 
height, aperture breadth and spire lengthof 171 snails from 9 localities were meas- 
ured and various ratios calculated in order to discover the nature of the relation 
between any two of these features. The angles of the spire and of the labrum de- 
pression were also measured. Only comparison with corresponding values ob- 
tained from other species will indicate which of these ratios differ sufficiently to be 
of use taxonomically. However, though the ranges of these values are in some cases 
ereat, the means for the 9 samples are usually fairly constant. An exception is the 
ratio shell length to spire length in which the mean values vary between 6.7 and 
15.2, The spire was, nevertheless, found to be relatively shorter in the smaller 
forms than in the large specimens. The apical spire angle is very variable: 58 °- 
134° . The mean value of the angle of labrum depression is 57° or 58° for all the 
localities except one for which the value is 61° . In respect of the shape of the aper- 
ture the adult shells usually fell in two main groups. This feature seems to change 
not only with the age of the snail, but probably also with varying ecological con- 
ditions. Although the columella region is fairly uniform in each sample it varies 
from one sample to the other. 

The osphradium was found to be present outside the mantle cavity on the collar. 
The gill (pseudobranch) is normal. The anal region differs slightly from previous 
descriptions in that the anal lobe seems narrower and the rectal ridge more dis- 
tinct. The length ratio Iddney/ureter was found to vary between mean values of 2.0 
and 4.6 in the various samples. 

Only two of the taxonomically important ridges are present on the roof of the 
mantle cavity, the renal ridge and the median rectal ridge being absent. The inter- 
mediate mantle ridge (between kidney and rectum) differs from the ñgure given by 
Mandahl- Barth (1956) in being longer and in always extending posteriorly to meet 
the lateral rectal ridge at the edge of the mantle cavity. 

An account is given of the blood vessels draining the gill (pseudobranch). The 
spherical bodies mentioned by Schutte and van Eeden (1959b) as occurring in the 
pericardial cavity oi Biomphalaria pfeifferi were found to be present in a large num- 
ber of specimens. They are thought to be the eggs of an unidentifled organism. 

(73) 



74 STIGLINGH, VAN EEDEN AND RYKE 

In the digestive system the j aw was found to differ from the descriptions offered 
in the literature and to conform to the general pattern for Bulimis. A study of the 
general proportions of the radula revealed that the mean ratio length/breath is fairly 
constant (2.4 - 2.6) and this ratio may therefore prove to be useful in comparison 
with related species. The sides of the teeth were found to be fluted and small den- 
ticles were detected between the cusps of the centrals and at the base of the meso- 
cone of the laterals. The mesocone of the laterals is almost never simply triangular 
as is stated by Mandahl- Barth (1956) to be the condition in the'ß. tropicus group. 
In certain instances it even approaches the arrowhead shape characteristic of the 
B. truncatus group. In spite of the known limitations of a radula formula, a gen- 
eralized formula for B. tropicus is offered: 1: 6+2 : 24 x 123. 

The names applied to the various ganglia of the circumesophageal ring are 
discussed and the nerves originating from them described. The salivary glands 
pass through the nerve ring. 

In the hermaphrodite gland there Is no division into male and female zones and 
the oocytes were found to have double nucleoli as is the case in certain other 
pulmonates. The carrefour region differs from that reported for the north American 
planorbid Helisoma trivolvis and agrees with the condition found in the African 
planorbid Biomphalaria pfeifferi. Attention is drawn to an irregular sac extending 
from the uterus and partly surrounding the base of the oviduct. In the prostate gland 
two main regions are distinguished, a peripheral opaque, yellowish region and a 
more translucent whitish central region. The occurrence of a short internal ridge 
in the proximal region of the penis is noted. The pilasters in the preputium extend 
as far as the junction of the latter with the penis sheath. The penis sheath/preputium 
ratio was found to vary considerably, but the means for the samples separately vary 
only beWeen 1.2 and 1.6. 



INTRODUCTION 

The interest in the African fresh-water 
snail Bidiniis (B.) tropicus (Krauss) has, 
up till now, been centered mainly around 
the veterinary and suspected medical im- 
postance of this species in so far as it 
is known to act as the intermediate host 
for the trematodes Paramphistomum and 
Cotylophoron and is closely allied to 
species which carry schistosomes of the 
haematobium group in Africa. There 
have been few serious attempts at a 
thorough investigation of the morphology 
of African planorbids. Much has been 
written on the problem of their classi- 
fication and although the crux of the mat- 
ter is the intrinsic variability of the 
species studied, numerous other factors 
have played a part in bringing about the 
general confusion on this issue which 
now exists. Probably the most important 
of these factors is that it was not ini- 
tially realised by the taxonomists that, 
in the case of B. tropicus, they were 
dealing with an extremely variable spe- 
cies. Even when the variability was re- 
cognized, the nature and causes thereof 
were not, indeed are not, properly under- 
stood. In certain instances a specimen 



may resemble one species of Bulimis in 
some respects and another species in 
others, so that it is almost impossible 
to ascertain to which species a particu- 
lar specimen in reality belongs. Further 
confusion arose from the fact that the 
criteria used in species discrimination 
were not always well chosen. When the 
shell alone was used to identify a spe- 
cies it was usually viewed as a dead, 
isolated object and neither the anatomy 
of the snail producing the shell, nor the 
ecological factors influencing it, were 
taken into account Finally there was the 
practice of sending snails for identifica- 
tion to overseas authorities who often 
applied different names to the various 
samples of the same species. In spite 
of Cawston's warning that only confusion 
would arise as a result of giving too 
many names, new names were freely 
applied, as is testified by the long, but 
by no means exhaustive, list of synonyms 
given in Connolly (1939). Schweiz (1952a) 
suggests certain remedies for this un- 
healthy state of affairs and the main 
ideas are that there should be a sound 
biological approach to these problems 
and that ultimate proof of relationships 



MORPHOLOGY OF BULINUS TROPICUS 



75 



should be obtained by carefully planned 
breeding experiments which, unfortunate- 
ly might also be subject to limitations. 

Besides the taxonomic tangle of con- 
fusion on the specific level, brief men- 
tion should also be made of some obscure 
relations on the subgeneric level. Wright 
(1957) considers B. hemprichii depressus 
Haas as a synonym of B. (Physopsis) 
globosus (Morelet) while Mandahl- Earth 
(1956) maintains that the former species 
is a synonym of B. (Bulinus) tropicus, 
whereas we are of the opinion that both 
these authors might be at fault. In view 
of these and other discrepancies much 
careful morphological study will yet be 
necessary in this group before the true 
specific or strain relations can be ac- 
curately assessed. 

Since bulinids represent the most com- 
monly occurring freshwater snails in 
South Africa, a closer investigation of 
the intraspecific variation of the shell of 
B. tropicus and certain aspects of its 
anatomy seemed to be indicated. The 
results of this investigation are dealt 
with in the present paper. 

MATERIALS AND TECHNIQUES 

Most of the material used in this study 
was sent, for identification, to this In- 
stitute by the staff of the Health Depart- 
ment of the Republic as part of the anti- 
bilharziasis programme in the Transvaal. 
Snails were collected from the following 
localities which will, in the text, be re- 
ferred to by the symbols indicated below. 



Locality 


District 


Province 


В - Beestekraal 


Brits 


Transvaal 


S - Sanddrift 


" 


" 


W - Wasgoedspruit 


Potchefstroom 


" 


D - Municipal Dam 


" 


" 


L - Native townsliip 


" 


" 


К - Kameeldrift 


Brits 


" 


A - Kameeldrift 






(locus 2) 


" 


" 


H - Shongwanstad 


Potgietersrust 


" 


M - Middelburg 


Middelburg 


" 


G - Grahamstown 


Grahamstown 


Cape Province 



It is to be regretted that none of these 
collection- sites represents the type lo- 
cality which Krauss (1848, p. 84) gives 



as "in flumine Lepenula (inter 25-26° 
lat. aust.)-" This river is subsequently 
designated as the Lepenula River (Pils- 
bry and Bequaert, 1927; Porter, 1938; 
Connolly, 1939; Mandahl- Barth, 1956) 
which, according to Porter (1938), must 
be somewhere in the Western Transvaal. 
Virtually all attempts to trace this river 
have failed, the only streams with more 
or less similar names being Lipalula, 
mentioned by Fuller (1932) and Lepelle, 
referred to by Baines (1877). The above 
localities were selected because snails 
collected from them resemble typical 
B. tropicus and also because, apart from 
Grahamstown, the localities are in the 
Transvaal. The number of specimens 
examined is as follows: - Beestekraal 
42, Wasgoedspruit 56 and at least 10 
from each of the remaining localities. 

The snails were narcotised and killed 
according to the method suggested by 
van Eeden (1958) which was found to give 
satisfactory results. In the case of long 
preserved specimens removal from the 
shell was facilitated by dropping the snail 
into boiling water for a few seconds. In 
some instances the expansion of air in 
the upper whorls caused the expulsion 
of the snail from its shell. Dissection 
was done under water in a petri dish 
having a black wax bottom. The mantle 
was removed and with it, part of the 
floor of the mantle cavity to include the 
proximal part of the rectal ridge. Much 
of the mantle was then trimmed away 
with a small pair of dissecting scissors, 
till only that part of the mantle bearing 
the kidney and intermediate mantle ridge 
was left. This was done so that the kid- 
ney could be pinned down as flat as pos- 
sible and with the minimum of stretching. 
In specimens not properly relaxed before 
fixing the mantle is wrinkled and in such 
cases it is impossible to smooth it out 
This seldom occurred. With the aid of a 
camera lucida or a micrometer grid and 
graph paper a line was traced down the 
middle of the kidney, from the beginning 
of the saccular part to the tip of the 
ureter. The line of the intermediate 
mantle ridge was also traced. These 



76 



STIGLINGH, VAN EEDEN AND RYKE 



lines were then measured using an opiso- 
meter (rotameter). 

Radula preparations were mounted in 
CMC 10 (a Turtox product), and a num- 
ber of these were drawn with the aid of 
a camera lucida. Whole mounts of 32 
penes were made using the technique of 
van Eeden (1958). The remaining penes 
were measured, using a micrometer eye- 
piece, in the following manner. The co- 
pulatory organ was removed together 
with a small portion of the vas deferens. 
A pin was inserted through the distal end 
of the preputium and the organ straight- 
ened, taking care that the preputium was 
not partially invaginated. The penis 
sheath was straightened by placing pins 
through the distal parts of the organ and 
through the vas deferens close to the 
point where it enters the penis sheath. 
For measurement of the penis and epi- 
phallus the proximal half of the penis 
sheath was removed and the penis and 
epiphallus exposed. (It is not necessary 
to open the penis sheath distally as the 
length of penis and penis sheath are the 
same in this region). The penis was 
then straightened by pinning down its 
proximal region, and then the epiphallus 
was unravelled, straightened and pinned 
down by a small piece of the penis sheath 
left at the junction of vas deferens and 
epiphallus. 

The shell, radula, penis and the rest 
of the soft parts of each snail were given 
a symbol and a letter to allow correla- 
tion of any peculiarities occurring and to 
allow comparison of snails from different 
localities and of different sizes. Snail 
specimens from localities В and W were 
serially sectioned, usually after having 
been fixed in formalin. To prevent the 
sand in the gizzard from damaging the 
microtome blade it is necessary to re- 
move the sand or entire gizzard, as sug- 
gested by Carriker and Bilstad (1946). A 
few specimens from W were fixed in 
Bouin's fluid. Serial sections were made 
of entire snails and, occasionally, of iso- 
lated organs. A few slides were stained 
with Masson's, but Mallory's triple stain 
proved to be more satisfactory. 



SHELL 

In spite of the fact that the shells of 
Bulinus species are " notoriously poly- 
morphic" (Cawston, 1938) yet, even in 
this genus, the shell exhibits certain 
characters by which the various groups 
and species are distinguished and which 
necessitate some reference to it in any 
morphological account of B. tropicus. 

The most complete descriptions of the 
shell of B. tropicus are those given by 
Krauss (1848), Germain and Neveu-Lemai- 
re (1926), Connolly (1931, 1939), Cawston 
(1938), all for South Africa, Mozley (1939) 
for Tanganyika, Mandahl-Barth (1954, 
1956) for Uganda and Southern Rhodesia, 
and de Azevedo et al. (1957) for Portu- 
guese East Africa. These all lead to the 
conclusion that there is no single descrip- 
tion of B. tropicus which will embrace 
all the diverse forms of this species and 
one has only to be confronted with a 
photographic series of shells like those 
published by Mandahl-Barth (1956), or 
indeed our own series (Figs. 1 and 2) 
most fully to realise this. 

The indications of size given in the 
literature are generally not very useful. 
Boettger's (1910) data are based on a 
few specimens or on one only. Krauss 
(1848) seems to have examined a number 
of shells while de Azevedo' s mean, based 
on a too small sample of 5 shells, is also 
unreliable. In his 1956 publication Man- 
dahl-Barth does, however, give mean 
measurements based on 25 specimens, 
which, unfortunately, are not always use- 
ful in comparative studies. 

The general appearance of the shell 
varies so much that several authors em- 
phasize this variability as a feature of 
the species. Thus the shell is described 
as pointed ovate (Mandahl-Barth, 1954), 
somewhat obese (Connolly, 1939) and 
oval and bulging (Germain and Neveu- 
Lemaire, 1926). 

The spire varies from slightly elevated 
(Mozley, 1939) to rather high, about half 
the length of the aperture (Mandahl-Barth, 
1956). 

Mozley (1939) notes that the shell con- 
sists of three whorls increasing rapidly 



MORPHOLOGY OF BULINUS TROPICUS 



77 



while Krauss (1838) and Germain and 
Neveu-Lemaire (1926) found shells with 
as many as five whorls, but four to four 
and a half convex whorls is the usual 
number (Mandahl- Barth, 1954, 1956; de 
Azevedo et al., 1957). The sutures may 
be very deep (Mozley, 1939; de Azevedo 
et al., 1957), deep (Germain and Neveu- 
Lemaire, 1926), or fairly deep (Mandahl- 
Barth, 1954, 1956). 

The colour of the shell is described as 
yellowish reddish, pale, shiny (de Aze- 
vedo et al, 1957), yellowish brown (Ger- 
main and Neveu-Lemaire, 1926), lighter 
or darker dull brownish (Mandahl -Barth, 
1956) or pale or dark horny brown (Man- 
dahl-Barth, 1954). According to Germain 
and Neveu-Lemaire (1926) the shell is 
rather solid while Mandahl-Barth (1954) 
and Mozley (1939) regard it as ''rather 
thin walled" and "thin walled" respec- 
tively. The sculpturing may consist of 
minute regular growth lines (Mozley, 
1939) or rather coarse growth lines (Man- 
dahl-Barth, 1956), in either case closely 
set. Krauss (1848) records that stria- 
tions on the last three whorls may, in 
juveniles, be covered by a thin membrane 
through which the costulations show. The 
nature of this membrane is not very 
clear. 

The aperture is oval (Germain and 
Neveu-Lemaire, 1926; Mozley, 1939; de 
Azevedo et al, 1957) and the labrum re- 
gularly curved (Mandahl-Barth, 1956) 
and simple (Krauss, 1848; Germain and 
Neveu-Lemaire, 1926; de Azevedo et al., 
1957). Krauss (1848) states that the la- 
brum is joined to the body whorl by a 
clear white shiny lamella, which, accord- 
ing to de Azevedo et al. (1957), is some- 
times indistinguishable from the labrum. 
The columella is straight (Mandahl-Barth, 
1954; de Azevedo et aL, 1957) and ac- 
cording to Connolly (1931, 1939) it may 
also be slightly concave. The columellar 
margin is generally widely reflexed (Man- 
dahl-Barth, 1956; de Azevedo et aL, 1957) 
and may either cover the umbilicus which 
is open from below (Krauss, 1848) or 
may only partially cover the umbilicus 
(Mandahl-Barth, 1954). The umbilicus 



is described both as narrow (Germain 
and Neveu-Lemaire, 1926; Mandahl-Barth, 
1956) and as broad and deep (Mozley, 
1959; de Azevedo et aL, 1957). 

From the above summary the fact 
emerges that these descriptions differ 
so much that they are often completely 
inadequate in species discrimination and 
the need for reducing verbal descriptions, 
wherever possible, to concise mathemati- 
cal terms becomes clear. Although sta- 
tistics cannot, in taxonomy, play the de- 
cisive role which it does in experimental 
work, it is nevertheless indispensable in 
bringing out correlations, differences, 
indications of variability, etc. In the 
present work the tatest and analysis of 
variance were not applied because the 
samples were collected by different peo- 
ple at different seasons. Bearing in mind 
that "it is the naturalis' s original sin 
to pay more attention to very small, or 
extra large or otherwise exceptional 
specimens" (Boycott, 1928, p. 28) our 
samples are most probably not random, 
and, except for those from localities W 
and B, are not large enough to compare 
classes of equal size, as was done by 
Schutte and van Eeden (1959a) for Biom- 
phalaria pfeifferi (Krauss). It was more- 
over not possible to compare data from 
modal classes since in some localities, 
e.g. К (Fig. 2), there were no specimens 
large enough to fall in the modal class. 
In any case Table I reveals that there 
is so little difference between the mean 
of the modal class and the mean of the 
total sample that the latter has been used 
wherever it might be expected to throw 
light on some aspect of the shell or soft 
anatomy. 

It has often been suggested and it has 
in some cases been demonstrated, among 
others by Simroth and Grimpe (1918), 
Baker (1938), Rotarides (1932), Wesen- 
berg-Lund (1939), Boettger (1944), Huben- 
dick (1941) and Schwetz (1954), that eco- 
logical factors influence the moUuscan 
shell in a number of ways. Unfortunately 
the very features known to be affected by 
ecological conditions are those most com- 
monly employed in taxonomic discrimina- 



78 



STIGLINGH, VAN EEDEN AND RYKE 



tion, e.g. size, shape, thickness of the 
shell, colour and sculpturing and our own 
observations can do no more than to 
underline the necessity of a closer in- 
vestigation of the relation between eco- 
logical factors and conchological features. 

Shells of B. tropicus from nine locali- 
ties (all but "L") were treated statisti- 
cally to discover correlations of changes 
in ratios and also in shell form and to 
find out which of these changes were de- 
pendent on increasing age of the snail. 

With regard to size it seems important 
to know the maximum length attained by 
any shell in the population, the mode of 
the sample, which is often of more use 
than the mean, and also the size range 
of the sample. Such data for one sample 
(W) are represented in Fig. 4. The 
largest shell in all our samples is 13.3 
mm but the modes of all the localities 
combined are only 9.2 and 10.0 mm. 
The size frequency, in a series of 171 
shells, determined to the nearest 1/10 of 
a millimetre is shown in Fig. 5. These 
dimensions cannot, however, be regarded 
as truly representative of B. tropicus as 
the size irregularity revealed by graphic 
representations should seem to indicate 
that the sampling was inadequate. The 
snails in sample К (Fig. 2) are all re- 
garded as young because they have the 



same general facies as juveniles in sam- 
ple W (Fig. 2) and the average length is 
only 7.2 mm. As they come from the 
same locality as sample A (Fig. 1) and 
were collected on the same day, the dif- 
ference in size between the samples 
seems explicable only by assuming that 
the juveniles, in this case, occupied a 
particular part of the habitat, different 
from that occupied by the adults. This 
supposition is further strengthened by the 
fact that the juveniles of sample W are 
thickly covered with sediment, a condition 
rarely found in adults and this, too, in- 
dicates that the juveniles may live under 
conditions slightly different from the nor- 
mal adult habitat. In this case they seem 
to prefer a more benthonic life. 

Series К indicates that size, which 
must obviously be influenced by eco- 
logical factors affecting growth, has an 
important effect on the general shape of 
the shell. In young snails (type I, Fig. 3), 
such as sample K, (Fig. 2) the whorls 
overlap each other greatly, resulting in 
the relatively large mouth aperture and 
a low spire. Here the base of the colu- 
mella is straight In the mature forms 
(Fig. 3) two further types (types II and 
III) of shell are distinguishable, depending 
on the tightness of the coiling of the 
whorls. In these older snails the whorls 



I 



TABLE I. Shell proportions in Bulinus tropicus. Comparison of the means and modes of modal 
classes of certain ratios for the 9 samples (W - G) separately and combined (T). 





e* n 


AH /AB 


В / AB 


L/ AH 


L / В 


AH / В 


AH / L 


A/ AH 


Samp] 


Mean Mode Mean 


Mode Mean Mode Mean Mode Mean Mode Mean Mode 


Mean Mode 


W 


47 


1.5 


1.5 


1.5 


1.5 


1.4 


1.5 


1.4 


1.5 


1.0 


1.0 


0.7 


0.7 


0.2 


0.2 


D 


12 


1.5 


1.4 


1.5 


1.4 


1.4 


1.4 


1.4 


1.4 


1.0 


1.0 


0.7 


0.7 


0.1 


0.1 


В 


40 


1.4 


1.4 


1.6 


1.6 


1.4 


1.4 


1.3 


1.3 


0.9 


0.9 


0.7 


0.7 


0.2 


0.2 


S 


11-16 


1.4 


1.4 


1.6 


1.6 


1.6 


1.6 


1.4 


1.4 


0.9 


0.9 


0.6 


0.6 


0.2 


0.2 


К 


10-11 


1.5 


- 


1.4 


- 


1.3 


- 


1.4 


- 


1.0 


- 


0.8 


- 


0.1 


- 


A 


12-15 


1.3 


1.4 


1.5 


1.5 


1.6 


1.6 


1.4 


1.5 


0.9 


0.9 


0.6 


0.6 


0.2 


0.2 


H 


10 


1.5 


1.5 


1.6 


1.5 


1.5 


1.5 


1.4 


1.5 


0.9 


1.0 


0.7 


0.7 


0.2 


0.2 


M 


10 


1.4 


1.4 


1.6 


1.5 


1.5 


1.5 


1.3 


1.3 


0.9 


0.9 


0.7 


0.7 


0.2 


0.2 


G 


10 


1.5 


1.5 


1.5 


1.6 


1.5 


1.5 


1.4 


1.4 


1.0 


1.0 


0,7 


0.7 


0.2 


0.2 


T 


162-171 


1.4 


1.4 


1.5 


1.5 


1.5 


1.5 


1.4 


1.4 


0.9 


0.9 


0.7 


0.7 


0.2 


0.2 



* see page 75 

n = number of specimens 



AH 
AB 



aperture height 
aperture breadth 



В = shell breadth 
L = shell length 



S = spire length 
T = total 



MORPHOLOGY OF BULINUS TROPICUS 



79 




FIG. 1. Photograph of representative specimens from localities B, M, S, A, and G. 



80 



STIGLINGH, VAN EEDEN AND RYKE 



w 



# 




^ Ф ^ 



D 



4' 




L I 



J 



2» 










Л 



H 



à à 




è f) 



к 



^ Ф ^ i^ 



10mm 



FIG. 2. Photograph cf representative specimens from localities W, D, L, H, and K. 



MORPHOLOGY OF BULINUS TROPICUS 



il 



do not overlap as much as in the juve- 
niles so that the height of the aperture 
(AH) is relatively smaller when compared 
with the total length of the shell (L). 
These proportions in the adult result in 
a higher value for the ratio L/AH (Table 
II). Type II is represented by sample H 
(Fig. 2). These snails have tightly wound 
whorls which are generally not highly 
convex. The shell is elongated and the 
umbilicus narrow. Although types I and 
II differ in details from figures 4 and 14 
(Physa zuluensis and Isidora compta) of 
Melvill and Ponsonby (1903), type I agrees 
with their Fig. 4, and t5фe II with their 
Fig. 14 (see Fig. 3). Type II is repre- 
sented by sample В (Fig. 1). This last 
type has whorls which are more convex 
than in the former two, and are not as 
tightly wound around the central axis, 
resulting in a more globose form with a 
wide umbilicus. 

It is often found that as the age of a 
snail increases, its shell assumes a more 
elongated form (Lais, 1925; Franz, 1928; 
Degner, 1930, quoted from Neuhaus, 1952). 
This observation is fully borne out, for 
B. tropicus, by Fig. 8 in which the ratio 
L/B (length/breadth) is plotted against L 
(length of the shell) and which also shows 
that, with regard to this ratio, only shells 
of approximately equal length should be 
compared. 



TABLE П. Means of the ratios shell length 
to aperture height (L/AH) and shell length to 
breadth (L/B) 








L/AH 




L/B 




Sample 


n 


Mean 


n 


Range Interval Mean 


W 


47 


1.4 


47 


1.2 - 1.6 


0.4 


1.4 


D 


12 


1.4 


12 


1.3 - 1.5 


0.2 


1.4 


В 


40 


1.4 


40 


1.1 - 1.5 


0.4 


1.3 


S 


16 


1.6 


11 


1.2 - 1.5 


0.3 


1.4 


К 


11 


1.3 


11 


1.3 - 1.5 


0.2 


1.4 


A 


15 


1.6 


15 


1.2 - 1.6 


0.4 


1.4 


H 


10 


1.5 


10 


1.3 - 1.5 


0.2 


1.4 


M 


10 


1.5 


10 


1.2 - 1.4 


0.2 


1.3 


G 


10 


1.5 


10 


1.3 - 1.6 


0.3 


1.4 


T 


171 


1.5 











n = number of specimens in sample 
T = total 

A few shells from each locality are 
reproduced in Figs. 1 and 2 to show the 
variation occurring in the series. The 
first few shells of each row are repre- 
sentative of the most "typical" shape 
occurring in the sample. As sample К 
(Fig. 2) consists of juveniles it is not 
clear into which type they would have 
developed, but, with two possible excep- 
tions, the shape of the shell seems to 
be correlated with the habitat. The shape 
of type II, represented by samples D, W, 
and H (Fig. 2) and type III, represented 
by samples B, S, and A (Fig. 1), could 
very well be the result of reaction to 





I II 

FIG. 3. L Immature form; II. Adult form; III. Adult form 



8á 



STIGLINGH, VAN EEDEN AND RYKE 




4-7 SPECIMENS 





7-5 lOO 

5HEL^ ^Ei^TH IN MM. 




4.0 4.5 





Э'5 40 4-5 

NO. OF WHORLS 




9 






8 






12-5- 




16 






L 
S 




L 






105 




В 










I-4- 






85 




1-2 












7-'5 10Ю 




7-5 100 

LENGTH IN MM. 


12-5 


I 1 




LENGTH IN MM. 


10 






I 1 

1-6 






16 






L 
AH 






АН 
AB 






1-4 






1-4 






12 












75 lOO 
LENGTH IN MM. 




7-5 100 
LENGTH IN MM. 







FIG. 4. Size frequency distribution of sample W (47 specimens). Modes of sample 10.1 and 

12.5mm- 
FIG. 5. Histogram of shell in all samples (171 specimens). Modes 9.2 and lO.Omm. 
FIG. 6. mstogram of the number of whorls in all samples (141 specimens). 
FIG. 7. Histogram of the ratio kidney to ureter (K/U) from 152 measurements. 



MORPHOLOGY OF BULINUS TROPICUS 



83 



running and stagnant water respectively. 
The globose, widely umbilicate type III 
is found in dams while the elongate, nar- 
rowly umbilicate type II is found in slow- 
flowing streams. These findings are in 
accordance with the view held by Sim- 
roth and Grimpe (1918), Baker (1928) 
and other authors, that the stream forms 
of certain gastropods are more elongated 
than those living in stagnant water. The 
two exceptions which do not fit into this 
picture are shells from locality L (pools) 
which show an elongated" stream" shape, 
and shells from locality M (a stream), 
which show a squat "pool" shape. In the 
last mentioned case the habitat contained 
many waterplants and thus the flow of 
water may have been hindered to such an 
extent that the habitat in which the snails 
lived may in reality have been a "pool" 
habitat 

Our deductions as to the presumable 
influence of ecological factors on the 
shape of the shell of B. tropicus do not 
match with the findings of Boettger (1944) 
working on various Lymnaea species. 
That author was primarily interested in 
the difference between lake forms in 
stagnant water, and those subject to wave 
action. Snails under the latter conditions 
were found to be short spired and obese, 
thus agreeing with what, in B. tropicus, 
seems to be the stagnant water form. 
Boettger also found that stream forms 
had rounded apertures, once more a char- 
acter apparently correlated with a pool 
habitat in B. tropicus. These apparently 
conflicting results may, perhaps, be as- 
cribed to the fact that the effects of run- 
ning water and waves, on the snail, are 
probably not the same. These diverse 



findings illustrate the need of detailed 
field studies, which were not possible in 
the present investigation as snails were 
sent to this Institute from various parts 
of the country. 

TABLE m. Mean ratios of shell length to 
spire (L/S) and the spire angles. 







L/S 




Spire angle 




Sample 


n 


Mean 


n 


Range Interval 


Mean 


W 


23 


9.7 


20 


81 - 113 


32 


97.6 


D 


12 


15.2 


10 


90 - 130 


40 


112.8 


В 


40 


9.2 


40 


80 - 134 


54 


93.5 


S 


16 


7.3 


10 


74 - 102 


28 


86.4 


К 


11 


12.5 


9 


90 - 119 


29 


104.4 


A 


15 


6.7 


10 


58 - 88 


30 


78.1 


H 


10 


8.0 


10 


75 - 104 


29 


87.9 


M 


10 


9.0 


9 


86 - 127 


41 


96.0 


G 


10 


9.3 


10 


87 - 102 


15 


93.6 



n = number of specimens 

The spire shape is rather characteristic 
in each of the samples and, as in Aus- 
tralian Bulinus species (Hedley, 1917, 
quoted from Gabriel, 1939) the spire 
length varies. This latter measurement 
was taken as indicated in Fig. 12. The 
general definition of spire length is shell 
length minus body whorl but in practice 
there are various ways of measuring the 
length of the spire. In this case we were 
interested in the general faciès of the 
shell, the relative lengths of the large 
body whorl and the smaller whorls above 
it, and for this reason the technically 
more correct method of measuring the 
spire (Burch, 1960) was not used. Table 
III demonstrates that the ratio of shell 
length to spire length (measured as indi- 
cated in Fig. 12), varies enormously. 



FIG. 8. Graph in which the ratio shell length to shell breadth (L/B) is plotted against the length 
of the shell (L). 

FIG. 9. Graph in which the ratio shell length to spire length (L/S) is plotted against the length of 

the shell (L). 
FIG. 10. Graph In which the ratio aperture height to aperture breadth (AH/AB) is plotted against 

shell length (L). 

FIG. 11. Graph in which the ratio shell length to aperture height (L/AH) is plotted against shell 
length (L). 



84 



STIGLINGH, VAN EEDEN AND RYKE 



both in the entire series and in each 
sample separately. In spite of this vari- 
ation there is an obvious negative corre- 
lation (Fig. 9) between this ratio and the 
length of the shell, proving that the small- 
er forms have relatively shorter spires. 
Mandahl-Barth (1956) gives the length of 
the spire as about half the height of the 
aperture. From Table I it can be seen 
that, in our series, the ratio of spire to 
height of the aperture, excluding samples 
D and К (Fig. 2) which have unusually 
short spires, is 0.2, i.e. only about one 
fifth of the aperture height. This dis- 
crepancy between our own and Mandahl- 
Barth's (1956) values may perhaps in 
part be explained by the fact that it is 
not quite clear how he measured the 
spire. The angle of the spire, measured 
as shown in Fig. 13 appears to be too 
variable to be of any use in taxonomy. 
From Table II it is apparent that shell 
types with spires as different in shape 
and length as К and A have spire angles 
of almost the same magnitude, while the 
total range of the whole series is 58° - 
1340. 

TABLE rv. Labrum depression angles in the 
shell of Bidinus tropicus. 



Sample 


n 


Range 


Interval 


Mean 


W 


12 


54 - 64 


10 


58.6 


D 


10 


53 - 60 


7 


58.3 


В 


40 


53 - 61 


8 


57.1 


S 


10 


53 - 62 


9 


58.6 


К 


9 


56 - 64 


8 


58.4 


A 


10 


52 - 65 


13 


58.8 


H 


10 


57 - 66 


9 


61.7 


M 


8 


55 - 62 


7 


57.3 


G 


10 


52 - 61 


9 


57.4 



n = number of specimens 

Fig. 6 reveals the variation in the 
number of whorls (3i to 4| ) of 141 speci- 
mens examined. The shell was placed 
vertically, the apex pointing upwards, in 
a small dish of sand and the number of 
whorls counted as shown by Mandahl- 
Barth (1954), using a binocular stereo 
microscope. In B. tropicus this is not 
very difficult as the whorls are convex 



and the sutures are clearly visible in 
this part of the shell. Although the in- 
crustation on shells from certain locali- 
ties obscured the sutures, this was easily 
removed by scraping the sutures with a 
fine needle since the snails were pre- 
served in glycerine alcohol. 

Hubendick (1951), working on Lymnaea 
pereger Müller, demonstrated that the 
thickness of the shell may be influenced 
by the surroundings. Our series seems 
to support this view, for shells from some 
localities are transparent and fragile 
whereas those from other localities are 
opaque and stout The colour likewise 
varies from a brownish yellow in the 
former to a yellowish white or a white 
in the latter. The real colour of the 
shell is often obscured by a coating of 
sediment which occurs sporadically. It 
is at times found only on the older whorls 
of the adult shell and is sometimes re- 
stricted to all the juveniles of a sample 
while in yet other cases only some of 
the juveniles may exhibit this feature. 

TABLE V. Ratios of shell breadth to aper- 
ture breadth (B/AB). 



Sample 


n 


Range 


Interval 


Mean 


W 


47 


1.4 - 1.7 


0.3 


1.5 


D 


12 


1.4 - 1.6 


0.2 


1.5 


В 


40 


1.4 - 1.9 


0.5 


1.6 


S 


15 


1.4 - 1.7 


0.3 


1.6 


К 


11 


1.4 - 1.5 


0.1 


1.4 


A 


12 


1.4 - 1.6 


0.2 


1.5 


H 


10 


1.5 - 1.8 


0.3 


1.6 


M 


10 


1.5 - 1.6 


0.1 


1.6 


G 


10 


1.4 - 1.7 


0.3 


1.5 



n = number of specimens 

The majority of shells in our series 
possess fine regular growth lines but a 
few are smooth while those from certain 
localities have pronounced narrow ridges. 
Boettger (1944) attributes such ridges in 
the Basommatophora and also other aqua- 
tic snails, to growth under exceptionally 
favourable conditions. In the Potchef- 
stroom area snails were collected from 
three localities, viz. from a stream (W) 
known as Wasgoedspruit, from the Muni- 



MORPHOLOGY OF BULINUS TROPICUS 



85 



cipal dam (D) and from temporary pools 
at the native township (L). The shells 
from locality W are elongated and fairly 
smooth, whereas those from localities D 
and L are more squat and have coarse 
transverse striations or ridges; attention 
though, should also be focussed on the 
sporadic occurrence of smooth forms in 
a sculptured population. The sculpturing 
in these three samples can be correlated 
with the shape of the shell: the elongated 
stream forms (type II) are smooth, while 
the squat "pool" forms (type III) are 
ribbed. These findings agree with the 
observations of Haas (1922) on various 
Naiads and on the prosobranch snail Vivi- 
parus costatiis Quoy and Gaimard, in 
which stream forms are smooth while 
the lake forms are sculptured. 

The varying aperture shapes in our 
series can be classified into three types 
coinciding with the three general types 
of shell referred to above (see Fig. 3, 

I, II, III). Fig. 10 reveals that the ratio 
aperture height to aperture breadth does 
not change as the snail becomes older 
and that the mean fluctuates between 1.4 
and 1.5 for all samples, except for the 
juveniles from locality К in which the 
ratio is 1.3. The graph plotted in Fig. 

II, which reflects the relation between 
shell length and aperture height, plotted 
against the entire length of the shell, 
shows a correlation, indicating that as 
the snail becomes older the mouth aper- 
ture becomes relatively smaller. Two 
additional ratios which might prove to 
be of taxonomic value are (a) shell 
breadth to aperture breadth (B/AB) and 
(b) aperture height to shell breadth 
(AH/B). The corresponding data for our 
specimens of B. tropicus are tabulated 
in Tables V and VI. Both the ratios 
B/AB and AH/B are fairly constant (see 
also Table I), the low value of B/AB for 
snails from locality К being due to the 
relatively large mouth aperture of im- 
mature forms. The shape of the aper- 
ture is partly determined by the shape 
of the columella which is usually straight, 
slightly concave or concave in the three 
shell types respectively. The columellar 



margin is broadly reflexed and its lower 
half is generally free and either covers 
the umbilicus when it is narrow, as in 
type II, or only partly covers the umbili- 
cus when it is wide and deep as in type 
III. The callus is usually well developed 
and of the same colour as the rest of the 
shell. It may also be either transparent 
and indistinct or white and sharply con- 
trasting. 

In sample В the labrum sometimes 
meets the body whorl in a very rounded 
angle, the aperture margin being slightly 
expanded like a trumpet This condition 
presumably represents that described by 
de Azevedo et al. (1957). The angle of 
depression of the labrum was measured 
by the method indicated in Fig. 14 and 
was found to be surprisingly constant 
(see Table IV), the mean varying by about 
one degree only in all localities (57. 1° - 
58.8°) except for H (61.7°) in which the 
shells are large and elongated and the 
labrum is more depressed than usual, 
thus producing a rather streamlined shell. 



TABLE 


VL Ratios of aperture heig 


ht to shell 






breadth 


(AH/B) . 




Sample 


n 


Range 


Interval 


Mean 


W 


47 


0.9 - 1.0 


0.2 


1.0 


D 


12 


0.9 - 1.0 


0.1 


1.0 


В 


40 


0.8 - 1.0 


0.2 


0.9 


S 


16 


0.8 - 0.9 


0,1 


0.9 


К 


10 


1.0 - 1.0 


- 


1.0 


A 


12 


0.8 - 1.0 


0.2 


0.9 


H 


10 


0.9 - 1.0 


0.1 


0.9 


M 


10 


0.8 - 0.9 


0.1 


0.9 


G 


10 


0.9 - 1.0 


0.1 


1.0 



n = number of specimens 

Because the length of the shell depends 
on so many factors, and is obviously not 
a reliable criterion for determining the 
age of the snail, both the number of 
whorls and the length of the shell were 
plotted against the number of transverse 
rows of radular teeth which have already 
been indicated by Hubendick (1945) and 
Schutte and van Eeden (1959) to increase 
with the age in some other basommato- 
phoran snails, to see which graph showed 



86 




STIGLINGH, VAN EEDEN AND RYKE 
13 : J4 




16 





15 







MORPHOLOGY OF BULINUS TROPICUS 



87 



the closer correlation. In both cases the 
scatter was so great that correlation was 
scarcely evident. This lack of corre- 
lation must partially be ascribed to the 
fact that there were not enough of the 
smaller shells. 

EXTERNAL MORPHOLOGY 

The animal has been described as blue- 
grey by de Azevedo et al. (1957) and, 
although this is true of preserved speci- 
mens, live animals are yellowish- or 
reddish brown as a result of the haemo- 
globin in the blood. Living specimens of 
B. tropicus have small white flecks due 
to concretions in the tissue such as occur 
in other planorbids (Baker, 1945; Abdel- 
Malek, 1952). The tentacles are filiform 
and circular in cross section although, 
in his 1946 publication on the anatomy 
of Bulinus Hubendick regards the tentacle 
as an outgrowth of the post-tentacular 
process and the latter as the homologue 
of the flattened triangular tentacles of 
the Lymnaeidae. Hubendick' s (1948) fig- 
ure of a cross section of the tentacle of 
B. (Physopsis) africanus (Krauss) (Plate 
2, Fig. 8) differs from ours for B. tropi- 
cus (Fig. 15) in being more solid, perhaps 
due to contraction. Throughout the length 
of the tentacle of the latter snail there 
is one central (C) and a number of peri- 
pheral cavities (P.C.) in the loose mus- 
cular tissue which is surrounded by a 
basement membrane (B.M.) supporting 
the external epithelium (E). The eyes 
are situated medially at the base of each 



tentacle (Fig. 19) and not at its outer 
side as mentioned by Mandahl- Barth 
(1954). Lateral processes occur at the 
base of the tentacle in the Bulininae, Pla- 
norbinae and Ancylidae (Hubendick, 1948). 
In B. tropicus there are two unequally 
developed processes, the dorsal tentacular 
process (D.T.P., Figs. 18 and 19) being 
more prominent then the ventral one 
(V.T. P., Fig. 18). Between them they 
enclose a ciliated groove, thus creating 
a condition resembling that found in spe- 
cies of Miratesta and Protancylus (Sim- 
roth, 1928). 

The gill (pseudobranch) (G), anal lobe 
(A. L.) and pneumostome (PN) are situated 
on the left hand side of the animal in the 
sharp angle formed by the junction of 
the labrum of the shell with the body 
whorL The natural relations of the vari- 
ous structures are most readily under- 
stood by referring to Fig. 19. The pneu- 
mostome is large and bounded ventrally 
by a small lobe referred to as the infe- 
rior palliai lobe, mantle lobe or lower 
mantle lobe by Hubendick (1946, 1955) 
and as the pulmonary siphon by Watson 
(1925) and pulmonary siphon and pneumo- 
stome by Baker (1945). The shape of the 
siphon varies constantly in a living animal 
where it is alternately protruded and 
retracted to collect air from the surface 
and then to convey it to the mantle cavity. 
The rectum opens at the tip of the anal 
lobe which is flattened dorso-ventrally 
and lies mediad to and slightly in front 
of the base of the gill. This region 
agrees more closely with Watson's (1925) 



FIG. 12. Diagram illustrating the method of measuring the length (CD) of the spire. 

FIG. 13. Diagram illustrating the method of measuring the angle (CA'D) of the spire. 

FIG. 14, Diagram showing the method of measuring the angle (CFE) of labrum depression. 

FIG. 15. Representative transverse section of tentacle at point anywhere between base and tip. 

FIG. 16. Transverse section of a kidney lamella. 

FIG. 17. Oblique section through the osphradium, situated on collar, outside mantle cavity. 

FIG. 18. Transverse section of the post- tentacular processes. 

FIG. 19. Dorsal view of the gill (pseudobranch) region. 

FIG. 20. View of ventral surface of roof of mantle cavity with attendant structures. 

See list of abbreviations p. 114 



88 



STIGLINGH, VAN EEDEN AND RYKE 



figure of Physopsis globosa (Morelet) 
{-Bulinus globosiis) than with Hubendick's 
(1955) figure of B. tropicus in that the 
anal lobe seems narrower and the rectal 
ridge more pronounced. The gill (G) is a 
U-shaped structure thrown into a number 
of large transverse folds alternately pro- 
truding on the dorsal and ventral surfaces. 
These could be called the primary folds 
(P. F.) of which there are 4 or 5 on each 
surface. Each of these primary folds 
consists of a number of smaller second- 
ary folds (S. F.) running in the same di- 
rection so that the large surface area, 
the thin epithelium and large blood spaces 
allow for the maximum oxygenation of 
the blood. As the mantle cavity of Buli- 
nus is generally filled with air, an os- 
phradium (O, Fig. 20) in its primitive 
position would be functionally useless in 
this species where, in fact, it lies out- 
side the mantle cavity on the collar, just 
medially to the pneumostome, and not just 
within the opening of the mantle cavity 
as claimed by Hubendick (1948). More- 
over this organ is much smaller than 
the one figured on page 30 by that author 
and agrees better with his earlier de- 
scription (1947) and withLacaze-Duthier's 
figure of the osphradium of Planorbarius 
corneus (Linné) reproduced in Boettger 
(1944, Fig. 95). A cross-section of this 
organ in B. tropicus is depicted in Fig. 
17. 

PALLIAL ANATOMY 

The mantle which only slightly overlaps 
the edge of the labrum of the shell has 
conspicuous black patches concentrated 
mostly over the kidney region. 

The renal system 

The kidney (Fig. 20) is well developed 
and consists of a proximal saccular (S.K.) 
and a distal tubular portion (Т.К.). The 
saccular part lies on the right hand side 
of the animal and posterior to the heart, 
while the tubular part roughly follows 
the border of the mantle cavity to the 
left hand side where it is reflected later- 
ally as the ureter (U), which is generally 



of the same thickness throughout The 
distal dilatation shown in Plate XXII by 
de Azevedo et al. (1957) is probably un- 
usual. In the snails we examined the 
saccular part is more distinct from the 
tubular part than appears to be the case _ 
in the figures of either Hubendick (1948) I 
or Mandahl- Barth (1946). The saccular 
portion possesses internal transverse 
ridges or lamellae (Fig. 16) which are J 
more pronounced in the tubular region. ' 
The ureter is usually smooth internally 
but a few small lamellae may occur. 
The lamellae may be fairly large but are 
never solid. Each lamella consists of a 
double layer of epithelial cells (E) which 
sometimes appear to be pseudostratified 
and are connected by fine, sparse con- 
nective tissue fibres among which numer- 
ous pigment cells may occur. A base- 
ment membrane (B.M.) is just visible 
underlying the epithelium. The whole 
structure is much less solid than that 
figured by Abdel-Malek (1952) for Heli- 
soma corpulentwn (Say), North American 
planorbid. Histologically the proximal 
region of the tubular portion of the kid- 
new differs from the distal region. In 
the former, cells are large, almost glo- 
bose, possessing conspicuous round bodies 
(U.C., Fig. 16) which are subsequently 
set free into the lumen of the kidney, as 
in certain Stylommatophora (Simroth 
1928), while distally the cells are much 
smaller and narrower. We found no trace 
of a longitudinal muscle on the ventral 
surface of the kidney. 

Hubendick (1955) contends that the mea- 
surement of organs is useless taxonomi- 
cally as the size may be affected to a 
varying degree by different types of fixa- 
tive. Although it is true that slight 
changes most probably do occur, and 
also that not all the snails are relaxed 
to the same degree, we cannot but support 
Schutte and van Eeden (1959a) in their 
rejection of Hubendick's (1955) statement. 
The kidney (K) and ureter (U) of B. tropi- 
cus were measured as already described 
under Material and Techniques and the 
ratio K/U calculated for 153 snails. Al- 
though the variation in each sample is 



MORPHOLOGY OF BULINUS TROPICUS 



89 



great, the values ranging from 2,0 - 4.6 
(Fig. 7), the different means show a fair 
degree of constancy. The mean for all 
the snails was 2.9, while the mean for 
30 snails of 7.7 mm and less was 2.7, 
and for 25 snails of more than 10 mm 
it was found to be 2.8, In other words 
there is a random variation of these three 
values which indicates that the ratio does 
not increase with age. 

The mantle ridges 

A feature of the mantle which is con- 
sidered to be of systematic importance 
in Planorbid snails (Mandahl- Barth, 1954, 
1956) is the presence of ridges which 
occur on the ventral surface of the man- 
tle and along the rectum. The confusion 
resulting from the nomenclature employed 
in describing these folds is dealt with in 
great detail by Schutte and van Eeden 
(1959a) and need not be recapitulated. 
In B. tropicus there are only two ridges 
the lateral rectal ridge (L.R.R., Figs. 
19, 20) and the intermediate mantle ridge 
(I.M.R., Fig. 20), the renal and the median 
rectal ridges being absent. A well de- 
veloped lateral rectal ridge is described 
for the Planorbidae in general (Baker, 
1945), for Physopsis globosa (=Buliniis 
globosas) (Watson 1925) and for various 
bulinids (Hubendick, 1955). In 5. tropicus 
this ridge originates as the flattened edge 
of the anal lobe (A.L., Fig. 19) and is 
continued posteriorly to terminate against 
the roof of the mantle cavity (M. CR., 
Fig. 20) near to its posterior margin. 
At this point it meets the intermediate 
mantle ridge (I.M. R.) which runs anteri- 
orly along the mantle between the rectum 
and the kidney, to end near the thickened 
mantle collar (COL). The degree of de- 
velopment of the intermediate mantle 
ridge, especially that part near the man- 
tle collar, is variable, but it is neverthe- 
less always distinct. No cilia were seen 
on this ridge in our specimens, but this 
fact may perhaps be attributed to the 
prolonged preservation, because the ma- 
terial was a few years old when dissected. 
However, seeing that the top of the ridge 
is covered by a layer of columnar epi- 



thelium while the sides are clothed with 
cuboidal cells, we assume that the ridge 
is in reality ciliated as it is in S. (Phys- 
opsis) africanus (Hubendick, 1948). The 
length of this ridge relative to that of 
the nephridium is used by Mandahl- Barth 
(1954, 1956) for distinguishing certain 
Bulinus species from each other. That 
author (1956) records that the intermedi- 
ate mantle ridge is much shorter than the 
kidney in the short spired species of 
Bulinus s. s. Although we found this ob- 
servation to be true, the ridge in our 
own series of snails is longer than that 
figured by Mandahl- Barth. 

The different means of the ratio: length 
of kidney (excluding ureter) to intermedi- 
ate mantle ridge, calculated separately 
for the nine samples studied, varies from 
1.4 - 1.9, while the mode and the mean 
of all the localities are 1.6 In 1954 
Mandahl- Barth expressed the opinion that 
the intermediate mantle ridge extends 
posteriorly as far as the mantle edge 
while he subsequently (1946) figures the 
ridge as ending between the rectum and 
kidney. In our series the former condi- 
tion is always realised. The rectal ridge 
bears cilia, as does the intermediate 
mantle ridge, and the epithelium of these 
ridges, of the collar and of the sole of 
the foot resemble that shown inBoettger's 
(1944) Fig. 44 for the marginal dorsal 
epithelium of the foot of Plmwrbarius 
CO meus (L.). 

The circulatory system 

The blood vessels of the mantle are 
depicted in Fig. 20. An account of these 
structures in the Planorbidae is given 
by Baker (1945) and Abdel-Malek (1952). 
The latter notes that the pulmonary vein 
(P.V.) supplies the gill (G). This is 
surprising since the blood in this vein 
should flow into the auricle (A) instead. 
From a dissection of B. tropicus it ap- 
pears that the gill is drained by the renal 
vein (R.V.) which proceeds posteriorly 
between the kidney and the ureter (U). 
It seems logical to assume that blood 
from this vein flows through the large 
vessels of the kidney into the pulmonary 



90 



STIGLINGH, VAN EEDEN AND RYKE 




MORPHOLOGY OF BULINUS TROPICUS 



91 



vein (P.V.) so that it would be more true 
to say that the latter drains the gill. 
The blood containing corpuscles which 
become red in Mallory's stain passes 
from the pulmonary vein into the auricle 
and thence into the less delicate ventricle 
(V) which has internal muscle strands 
(M.S., Fig. 22) resembling those found 
in the prosobranch snail Thiara granifera 
(Lamarck) (Abbott, 1952). From here the 
aorta (АО) supplies the structures indi- 
cated in Figs. 21 and 23. 

The pericardial cavity (PER, Fig. 22) 
is frequently filled with round, white 
structures thought to be the eggs of an 
unknown organism (EG). Although, in 
this instance, they were observed to be 
free from one another, they are probably 
identical with the strings of unidentified 
spherical bodies mentioned by Schutte and 
vanEeden (1959b) inBiomphalaria pfeifferi 
and also by Baker (1954). Cross-sections 
of these eggs are depicted in Fig. 27. 

INTERNAL ANATOMY 
Jaw and R adula 

In this system attention is focussed on 
only those features which are believed to 
be of taxonomic importance. In the Pia- 



no rbinae the jaw and the radula are taxo- 
nomically important (Baker, 1945) and 
the salivary glands are sometimes de- 
scribed. The jaw (J, Fig. 24) of B. 
tropicus is described and figured by 
Hubendick (1948) and de Azevedo et al. 
(1957). It forms the dorsal bar of the 
T-shaped mouth and, in specimens exam- 
ined by us, it differs markedly from that 
described by either of the authors men- 
tioned. Whereas Hubendick (1948, 1955) 
states that the jaw of S. tropicus is weak- 
ly developed and without lateral jaws 
(L.J.)>we found it to be well developed in 
all the specimens examined and composed 
of three elements as in other species of 
Bulinus. The dorsal horizontal portion 
(superior jaw) is generally broader dorso- 
ventrally, than indicated in Hubendick' s 
figure (p. 30, 1948) and snails from all 
nine localities possess lateral jaws. 
These are attached to the two extremities 
of the superior jaw and are folded behind 
to meet in the midline whence they de- 
scend vertically to form the upright por- 
tion of the mouth. Admittedly the lateral 
jaws may be poorly developed and they 
may even appear to be absent in cases 
where they are folded in by retraction 
of the buccal mass, as occurs in snails 



FIG. 21. 



FIG. 


22. 


FIG. 


23. 


FIG. 


24. 


FIG. 


25. 


FIG. 


26. 


FIG. 


27. 


FIG. 


28. 


FIG. 


29. 


See list of 



Diagrammatic sketch showing two of the three branches of the aorta (see also Fig. 23). 

АО. 2. 6. Vessel supplying caecum. 7. Vessel supplying oesophagus. 8. Vessel supplying 
cardiac stomach. 9. Cephalic artery to buccal mass. 10. Vessel supplying al- 
bumen gland. 

A0.3. Vessel passing over the stomach to the intestine. 

Heart with structures suspected to be the eggs of some unidentified organism in the 
pericardial cavity. 

Diagrammatic sketch of one of the three branches of the aorta. 

AO.l. 1. Vessel to the intestine. 2. & 3. Vessels supplying the stomach. 4. Vessels sup- 
plying caecum. 5. Vessel supplying liver. 

The superior and lateral jaws. 

The salivary glands and their relation to the nerve ganglia of the circumoesophageal 
region. 

Transverse section through a salivary gland near posterior end. 

Section through one of the eggs shown in Fig. 22. 

Statocyst on a pedal ganglion. 

View of the buccal ganglia and their nerves as seen when the buccal mass is tilted for- 
ward so that its posterodorsal surface faces upwards (diagrammatic). 

abbreviations p. 114 



92 



STIGLINGH, VAN EEDEN AND RYKE 



killed in boiling water. De Azevedo et al. 
(1957) describe the jaw as biconvex, a 
shape assumed by none of the jaws of 
our series. 

The length/breadth ratio of the radula 
was found to be fairly constant, both for 
snails from different habitats and of dif- 
ferent sizes (Table VII). That this con- 
stancy is of taxonomic importance has 

TABLE VII. Values of the ratios length to 
breadth (L/B) of the radula in the samples 
separately, combined (T) and for snails with 
shells of 7.7 mm and less and with shells 
larger than 10.0 mm. 



Sample 



n Range Interval Mean 



W 
D 
В 
S 
К 
A 
H 
M 
G 
L. 1.1 : 



46 

11 

31 

6 

7 

9 

8 

10 

9 

30 



- 3.0 

- 3.1 

- 2.7 

- 2.6 

- 2.9 
2.3 - 2.7 
2.2 - 2.9 

2.7 
2.8 



2.1 
2.2 
2.1 
2.3 
2.3 



2.2 

2.2 



2.3 - 2.9 



0.9 
0.9 
0.6 
0.3 
0.6 
0.4 
0.7 
0.5 
0.6 
0.6 



> 10 mm 24 2.2 - 3.1 0.9 



2.5 
2.5 

2.4 
2.4 
2.6 
2.4 
2.6 
2.4 
2.4 
2.5 
2.5 



134 2.1 - 3.1 



1.0 



2.5 



n = number of specimens 

not been proved and the data are given 
merely to facilitate future comparative 
studies. In the case of Biomphalaria 
pfeifferi this ratio was found to vary be- 
tween 2.15 and 3.09 (Schutte and van 
Eeden, 1959a), whereas inBidinus tropicus 
it varies between 2.1 and 3.1. When 
dealing with the Bulininae, Mandahl- Barth 
(1956) emphasizes the importance of the 
relative size of the teeth and, in certain 
cases, the shape of the first lateral, while 
he apparently finds the shape of the mar- 
ginals more important as a means to 
characterize the different species of the 
Planorbinae. In describing B. tropicus 
he refers to the radula merely by saying 
that the teeth are rather small. From 
the data in Table VIII it is seen that, 
considering their small size, the size of 



TABLE VIII. Height of the crown of the cen- 
tral and first lateral tooth in mm, calculated 
from the published figures of other authors 
and from two of our own specimens. 



Author 


Central 


Lateral 


Connolly, 1939 


0.009 


0.01 


Hubendick, 1947 


0.01 


0.01 


Cawston, 1926 


0.02 


0.03 


Mandahl-Barth, 1956 


0.007 


0.01 


de Azevedo et al. 


0.006 


0.009 


1957 






Stiglingh, van Eeden 






and Ryke; specimens: 






B13: 10.0 mm 


0.01 


0.02 


B41: 5.84 mm 


0.010 


0.012 



the teeth varies considerably. The dis- 
crepancy in the sizes of teeth may be 
partly accounted for by differences in the 
age of the snails for it is known that 
with increasing age the teeth change not 
only in chemical composition (Verdcourt, 
1948), but also in size (Hubendick, 1955). 
That this is not the only factor concerned 
is suggested by the fact that although our 
specimens B^i and Bj^ß differ much in 
length, being 5.84 mm and 10.0 mm re- 
spectively, the teeth of the former are 
still larger than those described by Con- 
nolly (1939), Mandahl-Barth (1956) or de 
Azevedo et al. (1957) (Table VIU). As 
the teeth are very similar within this 
family, verbal descriptions are insufficient 
to bring out the critical differences, and 
should be supplemented by figures. The 
figures given by many authors such as 
Cawston (1925), Hubendick (1948) and de 
Azevedo et al. (1957) unfortunately leave 
much to be desired, a fact which makes 
a careful comparison of radulae difficult. 
Some figures are thickly drawn and in- 
distinct, some are minute and fine lined 
while in yet other instances the laterals 
and marginals are left unnumbered. 

In our work it was observed that the 
centrals vary much in the shape of their 
cusps which may be broad and relatively 
far apart (Fig. 31) or narrow and more 
upright in position (Fig. 32), while there 



MORPHOLOGY OF BULINUS TROPICUS 



93 



may also be a small denticle between the 
two main cusps. In all the specimens 
of 5. tropicus examined under oil immer- 
sion the sides of the crown have a more 
or less fluted (Fig. 30) appearance, al- 
though it may not always be very evident, 
a circumstance which probably explains 
why this feature, which also occurs in 
other types of tooth, has not yet, to our 
knowledge, been recorded in the litera- 
ture. The crown may also be relatively 
smaller when compared with the base and 
this always appears to be the case when 
the central is slightly out of focus on 
account of its having been pushed out of 
position by pressure on the coverslip. 
The shape of the base differs from that 
shown by Cawston (1925, 1926). Nowhere 
did we see the rounded corners of the 
broad end of the base figured by that 
author. In some cases the base ap- 
proaches the trapezoidal shape shown by 
Mandahl- Barth (1956) although it is usu- 
ally more horned, resembling the figures 
by Connolly (1939) and de Azevedo et al. 
(1957), and yet not quite like either. 

The laterals (Figs. 30, 33) are larger 
than the centrals and almost invariably 
have a tiny denticle at the base of the 
mesocone (ME), either on one side or 
on both. The first lateral is a broad 
tooth, fluted medially, while the cutting 
edges of the ecto- (EC) and endo cones 
(EN) adjacent to the mesocone may be 
concave, straight or convex. The meso- 
cone is almost never simply triangular 
as is claimed by Mandahl-Barth (1956). 
Usually the two sides converge slowly 
from the base and then suddenly slope 
more sharply towards the apex, the la- 
teral side of the triangle being longer 
than the median. In this respect the 
mesocones differ from the mesocone de- 
scribed and figured by Mandahl-Barth 
(1956) for the B. tropicus group and yet 
by reason of the more acute apex of the 
cusp and the longer lateral side of the 
triangle they are usually distinct from 
those found in the B. truncatus group. 
The radulae of snails from locality G 
(Fig. 34) are an exception to this in that 
their mesocones strongly resemble those 



of the truncatus group which might indi- 
cate either that the Grahamstown speci- 
mens do not belong to the tropicus group 
at all, or that the shape of the mesocone 
does not always constitute a reliable ba- 
sis to distinguish between the tropicus 
and truncatus groups of Bulinus as claim- 
ed by Mandahl-Barth (1956). However it 
might perhaps be premature to suggest 
the latter explanation. In all samples 
the base of the lateral tooth is relatively 
smaller than that of the centrals and the 
tooth is not like any figured in the litera- 
ture. It approximates that shown by 
Mandahl-Barth (1956) but actually it is 
closest to Schutte and van Eeden's (1959a) 
figure for Biomphalaria pfeifferi. Pro- 
ceeding laterally in the radula the teeth 
become progressively more obliquely 
placed and the ectocone comes to lie 
lower than the endo- and mesocone. 
Gradually the last- mentioned two cusps 
are replaced by 5 - 9 denticles while 
1-5 denticles appear laterally at the 
base of the ectocone. At the same time 
the tooth becomes more elongate till it 
assumes the shape typical of a marginal 
(Fig. 33). There is no clarity or uni- 
formity as to how the various authors 
distinguish between lateral and marginal 
teeth, and as the transition is so gradual 
and variable, we have for the sake of 
objectivity, regarded the first marginal 
tooth as one in which the endo- and meso- 
cone are represented by at least three 
denticles of approximately equal size or 
four denticles which may be of unequal 
size. In counting the teeth we therefore 
located the first marginal and then pro- 
ceeded medially counting the teeth be- 
tween this and the central, thus grouping 
the atypical laterals or so called inter- 
mediate teeth of Schutte and van Eeden 
(1959 a) and de Azevedo et al. (1957) 
which, in B. tropicus, vary in number 
from 0-2, with the typical laterals. 
This procedure is also reflected in the 
radula formula. A distinction between 
what is typically lateral, intermediate 
and typically marginal is not feasible in 
B. tropicus , where the transition from the 
first to the last mentioned is much more 



94 



STIGLINGH, VAN EEDEN AND RYKE 




31 







FIG. 30. First lateral tooth illustrating the various parts. 

FIG. 31 - 32. The two types of central tooth of the radula, with and without central denticle. 
FIG. 33. Central tooth and half of a transverse row (1 - 29) of a specimen from sample B. 
FIG. 34. First lateral teeth of specimens from sample G. 

See list of abbreviations p. 114 



MORPHOLOGY OF BULINUS TROPICUS 



95 



gradual than in Biomphalaria pfeifferi. 

The marginals (Fig. 33) are elongated 
and obliquely placed. The tooth is fluted 
medially and the denticles occasionally 
have bifid tips. The denticle which re- 
presents the mesocone of the lateral teeth 
is broader and higher than the other den- 
ticles. Sometimes it is evenly rounded 
laterally, but more typically it is angular. 
Lateral to the ectocone there are up to 
5 small denticles which may increase in 
number so as to produce a serrated la- 
teral margin. The crowns of the extreme 
marginals have reduced denticles and 
occasionally unicuspid marginals, similar 
to those described forS, pfeifferi (Schutte 
and van Eeden, 19 59a), seem to occur. 
On close inspection, however, these most- 
ly turn out to be ordinary marginals seen 
edge-on. The base of the marginal tooth 
is more elongated than any figured in 
current literature. Besides the teeth 
described above, a variety of abnormally 
shaped teeth may occur throughout a lon- 
gitudinal row but these are easily recog- 
nised as anomalies and merit no further 
attention. 

Several authors have thus far given 
radula formulae for Bulinus tropicus but 
these, unfortunately, are not always in 
concurrence with each other. Thus, 
Connolly (1939) gives the formula as 
1:8:22 x 90+n, and that given by de Aze- 
vedo et aL (1957) is 1:25 x 121. Cawston 
(1925, 1926) gives no formula but sets 
the number of laterals at 8. The limi- 
tations of these formulae and the possible 
causes for the different results have al- 
ready been dealt with by Schutte and van 
Eeden (1959a) whose views are fully borne 
out by our investigation of B. tropicus. 
While 8 laterals seem to be a constant 
mean, the actual number varies from one 
radula to another, and even from one 
transverse row to the other. The number 
of marginals to a transverse row like- 
wise oscillates greatly and, moreover, 
increases with the age of the snail. In 
B. tropicus the issue is further compli- 
cated by the fact that there is no satis- 
factory criterion for distinguishing be- 
tween the various t5фes of tooth. Finally 
the number of transverse rows reflected 



in the formula has been proved to in- 
crease with the age of the snail in the 
case of Biomphalaria pfeifferi (Schutte 
and van Eeden, 1959a). Correspondingly, 
in B. tropicus the mean number of rows 
for snails having shells of 7.7 mm and 
less is 113, whereas the mean number 
of rows for snails having shells larger 
than 10 mm is 134. Bearing in mind 
the shortcomings of any such formula, 
we nevertheless offer one as it may, in 
certain respects, be useful. From our 
own investigations of 92 radulae from 9 
localities and from a random selection 
of a few from each locality in which the 
relative numbers of teeth were counted, 
a representative formula for B. tropicus 
seems to be 1 : 6+2 : 24 x 123. In this 
formula the number 2 represents the 
intermediate teeth which are neither typi- 
cally lateral nor typically marginal. 

The Salivary glands 

The salivary glands (Fig. 25) are very 
uniform in the Planorbidae (Baker, 1945), 
where they are usually long and cylin- 
drical Contrary to Hubendick's (1948) 
account of the condition in B. tropicus, 
in which he states that the glands do not 
pass through the nerve ring, they do pass 
through it, narrowing considerably as 
they do so and then becoming larger pos- 
teriorly. The end of the loop is attached 
to the oesophagus or body wall or both 
of these, and at this point receives a 
blood vessel. Although they may some- 
times have slight constrictions they are 
not moniliform as in the case of Physop- 
sis globosa (=B. globosus) (Watson, 1925). 
Except for the fact that there is not much 
more of the gland behind the nerve ring 
than there is in front of it. the lengths 
being about equal, Watson's (1925) de- 
scription is applicable to B. tropicus. 
Histological detail of the gland is shown 
in Fig. 26. It appears that the structure 
is more or less the same throughout the 
length of the gland, except at the very 
thin part passing through the nerve ring, 
where the cells do not show signs of such 
active secretion as in the parts with 
larger cells. 



96 



STIGLINGH, VAN EEDEN AND RYKE 



Nervous system 

At the higher taxonomic levels the ner- 
vous system is generally considered reli- 
able for comparative studies. It was 
unfortunately not possible for us to study 
the reports of the nervous system in vari- 
ous Basommatophora as presented by 
Lacaze-Duthiers (1872), Pelseneer (1895), 
and Elo (1938) but accounts or short 
notes are also found in Watson (1925), 
Simroth (1928), Boettger (1944), Baker 
(1945) and Hubendick (1947, 1948). Some 
of Pelseneer' s figures are reproduced 
in Boettger (1944) and Simroth (1928) 
while the last mentioned author also re- 
produces figures by Lacaze-Duthiers.l 

Hubendick (1947) is of the opinion that, 
allowing for the differences resulting 
from being coiled sinistrally ordextrally, 
the nervous system of the Planorbidae 
shows a maximum agreement with that 
of the Lymnaeidae and Physidae, in which 
the system consists of a concentrated ring 
of ganglia surrounding the oesophagus. 
There are many designations for the pos- 
terior three ganglia of the ring. However, 
the most commonly used appear to be 
parietal and visceral for the lateral and 
median ganglia respectively. 

A semi-diagrammatic sketch of the 
circumoesophageal ganglionic ring in B. 
tropicus, indicating the major nerves 
issuing from the ganglia, is given in Fig. 
35. The ganglia are paired except for 
the hindmost, median visceral ganglion. 
Each cerebral ganglion (CG.) is composed 
of a large dorsal and a smaller ventral 
lobe, though variations occur not only as 
regards the general shape of the ganglia 
which sometimes possess numerous small 
lobes, but also in the surface which may 
be quite smooth or have the appearance 
of a mulberry. These ganglia and the 
nerves issuing from them differ in a 
number of details from the generalized 
description for the Basommatophora given 



by Boettger (1944). That author reported 
seven pairs of peripheral nerves, origi- 
nating from the cerebral ganglia: nervus 
opticus, n. staticus, n. tentacularis, n. 
fronto -labialis superior, n. labialis médi- 
us, п. labialis minor, n. nuchalis and an 
additional unpaired п. penis on either the 
right side in dextral forms, or on the left 
side in sinistral forms. In the B. tropicus 
snails examined we recognised only six 
(not seven) paired nerves from the cere- 
bral ganglion, which did not arise in the 
order mentioned by Boettger (1944). The 
first nerve to arise from the dorsal lobe, 
(from front to back) is the stout tentacular 
(T.N.) which proceeds to the base of the 
tentacle where it joins a ganglion which 
Simroth (1928) describes as the cup-shaped 
ganglion. In B. tropicus the ganglion is 
elongated and grooved laterally in con- 
formity with the post-tentacular groove. 
The fine ocular nerve arises just posterior 
to the tentacular nerve and agrees entirely 
with Simroth' s description of it. A third, 
extremely delicate nerve originates at the 
posterior edge of the dorsal lobe of the 
dorsal lobe of the cerebral ganglion and 
innervates the statocyst (ST) associated 
with each pedal ganglion (PE. G). The 
inferior (ventral) cerebral lobe also gives 
rise to three nerves. There are two (not 
three) labial nerves (L.N.), of which the 
more slender anterior one branches in 
two. On the left side only, at the point 
or origin of the more posterior labial 
nerve, and before the last of the paired 
nerves, arises the penial nerve so that 
the left cerebral ganglion has seven 
nerves. The last nerve is about as fine 
as the one supplying the statocyst and 
proceeds mediad to innervate the walls 
of the cephalic artery. 

Finally the cerebro-buccal connective 
(C.B. C., Fig. 25) arises from the inferior 
cerebral lobe on either side. The inter- 
buccal connective is so short that the 
buccal ganglia (B.G., Figs. 25 and 29) may 



^The nervous system among others, of a related species of Bulinus has been described in detail by 
Demian (1960, Morphological studies on the Planorbidae of Egypt I. On the macroscopic anatomy 
of Bulinus (Bulinus) trunca tus (Audouln). Ain Shams Sei. Bull. No. 5 (Monograph), 84p,, 9 pi.. 
Faculty of Science, Cairo). ED. 



MORPHOLOGY OF BULINUS TROPICUS 



97 



be contiguous. The origin and distribution 
of tlie buccal nerves (Fig. 29) agree with 
Watson's (1925) findings. 

The pleural ganglia (PL.G., Fig. 35) 
agree with Boettger's (1944) account in 
being small and in having no peripheral 
nerves. 

The parietal ganglia (PA.G., Fig. 35) 
are asymmetrical, the left being at least 
twice the size of the right. As in Boett- 
ger's (1944) description for Platwrbariiis 
corneus (L.) (after Merker), the right 
parietal ganglion in B. tropicus has only 
one nerve, the collar nerve (C.N'.). This 
nerve also splits into two, the anterior 
branch innervating the anterior part of 
the collar and the other branch curving 
around to that part of the collar which 
overhangs the foot posteriorly. Boettger' s 
descriptions of the left parietal and the 
visceral ganglia do not coincide with the 
conditions obtaining inS. tropicus, where 
each of these ganglia has one nerve less; 
the left parietal ganglion has three nerves. 
The largest of these (OS.N.) corresponds 
to the single nerve of the right parietal 
ganglion and has two main branches, one 
(PN.N.) innervating the dorsal lip of the 
pneumostome and giving off a tiny branch 
to the ureter, while the more ventral 
branch (OS.N.) supplies the osphradium 
and the collar. The remaining two pari- 
etal nerves are very fine, the median, 
or body wall nerve (B.W.N.) arising be- 
tween the parietal and visceral ganglia 
and running backwards along the cephalic 
artery to supply the anterior body wall 
at the level of the base of the uterus, 
while the lateral nerve joins a branch 
(G.N.) from the stoutest and most pos- 
terior abdominal nerve at the level of the 
collar. 

The single visceral ganglion bears three 
nerves. The stoutest of these passes 
just posterior to the vagina and then splits 
into three, a small branch (S.N.) going 
to the siphon (ventral lobe of the pneu- 
mostome), a branch (G.N.) supplying the 
median part of the gill, and a third branch 
(C.N".) supplying the collar posterior to 
the gill. In this respect the situation 
differs from the descriptions seen in the 



literature, where it is stated that the gill 
is supplied by the left parietal ganglion, 
while only a thin connection leads from 
that ganglion to the combined gill and 
collar nerve in B. tropicus. The uterine 
nerve (U.N.) just antero-dorsal to the gill 
nerve, runs between the uterus and colu- 
mellar muscle and sends small branches 
to both, as well as a small branch to the 
prostate gland. It also has a very fine 
branch supplying the cephalic artery. 
The third nerve (B.R.N.), which is also 
very fine, arises from the right side of 
the ganglion and supplies the right retrac- 
tor muscle of the buccal mass. 

The pedal ganglia (PE.G.) are almost 
as large as the cerebral and agree with 
Boettger's (1944) account in having six 
nerves. Three of these (PE.N.) are stout 
and innervate the anterior, median and 
posterior portions of the foot, while three 
more slender dorsal nerves (LAT.N.) 
supply the body wall, generally at the 
level of the lateral muscle bands. In 
addition to the ganglia already mentioned 
there is, situated posterior to the inter- 
pedal connective, a minute little ganglion 
which sends a few fibres to the foot. A 
conspicuous white statocyst (ST, Fig. 28) 
containing highly refractile crystals is 
placed postero- dor sally on each of the 
pedal ganglia. 

Reproductive System 

The general appearance of the genital 
system is depicted in Fig. 41. 

Hermaphrodite System 

The histology of the hermaphrodite 
gland has been described for various 
snails such as the Pulmonata generally 
(Simroth, 1928), the Basommatophora 
(Boettger, 1944), some Planorbidae (Ab- 
del- Mai ek, 1952), Bulimis (B.) contortus 
Michaud (=S. truncatus Audouin) (Laram- 
bergue, 1939) and for B. (Physopsis) 
jousseaumei (Dautzenberg) (Wright, 1957) . 
The general morphology of the ovotestis 
of B. tropicus agrees with that of Phy- 
sopsis globosa i^-Bulinus globosus) fig- 
ured by Watson (1925), and with Abdel- 



98 



STIGLINGH, VAN EEDEN AND RYKE 




AL.GL 



M. GL. 



MORPHOLOGY OF BULINUS TROPICUS 



99 



Malek's (1952) description for Helisoma 
trivolvis Say. The number of acini (AC, 
Fig. 41) most commonly varies between 
14 - 16 in the longest of the longitudinal 
rows, of which there are 3 - 4 at the 
widest part of the gland. Only the long- 
est of the longitudinal rows extends as 
far as the apex of the organ. The acini 
are arranged with their narrow bases 
opening into the tubular common atrium 
(C.A.) which is continuous with the her- 
maphrodite duct (H.D.). 

As noted by Abdel-Malek (1952) the 
ovotestis is surrounded by a pigmented 
connective tissue layer which is most 
densely pigmented over the apices of the 
acini. The germinal epithelium of B. 
(B.) tropicus lines only the basal portion 
of each acinus (Fig. 37) so that in this 
respect it agrees with B. (B.) contortus 
(Larambergue, 1939) and B. (P.) jous- 
seaiimei (Wright, 1957), but differs from 
both Planorbis planorbis (L.), a pale- 
arctic planorbid, where the germinal 
epithelium is restricted to the common 
atrium (Boettger, 1944) and Arianta ar- 
bustorum (L.), a stylommatophoran snail, 
where this epithelium seems to be present 
in the apical portion of the acinus as 
well (Simroth, 1928, Fig. 205A). Like 
Larambergue (1939) in B. contortus, we 
can see no differentiation of the ovotestis 
into male and female zones, the two kinds 
of sexual element occurring intermingled. 

The oocytes (ОС, Figs. 36 and 37) have 
double nucleoli (N1), a condition also oc- 
curring in species of the terrestrial pul- 
monates Helix 2ináArion{Ancel and Lams, 
quoted from Simroth 1928). Each nucle- 
olus consists of two opposed spherical 



bodies, one slightly smaller and staining 
more deeply than the other. 

Regarding the pulmonates, Simroth 
(1928) claims that as soon as the undif- 
ferentiated cells of the germinal epithe- 
lium become differentiated into male ele- 
ments they leave the syncytium and com- 
plete their development in the lumen of 
the acinus. This observation is apparent- 
ly supported by Abdel-Malek (1952) who 
mentions sperm bundles occurring free 
in the lumen in Helisoma trivolvis. Our 
own impression is that, in B. tropicus, 
the sperm bundles (S.B., Fig. 37) may 
either be free in the lumen or attached 
to the basal or Sertoli cells, a view also 
put forward by Wright (1957), although 
transverse sections through the basal 
part of the acinus reveal the basal cells 
(B.C., Fig. 36) attached to its walls, thus 
also lending support to Boettger (1944) 
who maintains that the basal cells never 
float in the lumen. The spermatogonia 
(SO) spermatids (STD) and sperm cells 
(SP) are easily recognisable as such and 
present no noteworthy features. 

The hermaphrodite duct (H.D., Fig. 41) 
is tubular both proximally, i.e. nearest 
to the ovotestis, and distally, but the mid- 
dle region has closely arranged irregular 
seminal vesicles (V.S.), and is convoluted, 
so that the whole appears as a solid and 
rather wide structure. Where the her- 
maphrodite duct splits into the male and 
female ducts, which are completely sepa- 
rate in this case, it receives the duct 
from the albumen gland (AL. GL.). 

The mutual relations of these ducts 
are shown in Fig. 38. Basically they 
agree with the figures for B. contortus 



Dorso-lateral view of the circumoesophageal ganglionic ring and its main associated 
nerves (diagrammatic). 

Section showing oocyte and sperm in apical part of acinus. 

Section of an acinus of the ovotestis. 

Sketch of the carrefour region (dorsal view). 

Section of a penis in the spermatheca. 

Drawing of the dorsal surface of the uterus. 

FIG. 41. Illustration of the reproductive system (excluding the penial complex). 

See list of abbreviations p. 114 



FIG. 


35. 


FIG. 


36. 


FIG. 


37. 


FIG. 


38. 


FIG. 


39. 


FIG. 


40. 



100 



STIGLINGH, VAN EEDEN AND RYKE 



by Larambergue (1939) and for Biom- 
phalaria pfeif feri by Schutte and van 
Eeden (1959b), both belonging to Ethiopian 
planorbid subfamilies, but differ from 
that given by Abdel-Malek (1952) for Heli- 
soma trivolvis, a nearctic planorbid. In 
B. tropicus the duct of the albumen gland 
is short and opens into a pear-shaped 
sac, the carrefour (CAR), embedded in 
the hilus of the albumen gland. This sac 
is lined by ciliated cuboidal cells with 
large nuclei. The proximal end of the 
oviduct (OD) is folded back on itself and 
lies lateral to the carrefour to which it 
is connected by means of a short wide 
duct into which both the hermaphrodite 
duct and the sperm duct (SP.D.) open. 
Wright (1957) also mentions a carrefour 
in B. (P.) jousseaumei which, although 
not figured, seems to agree with that 
described by Abdel-Malek (1952) in being 
a dilatation of the oviduct a short dis- 
tance from its point of origin. Even 
though this structure does not seem to 
us to be homologous with that occurring 
in B. tropicus, we follow the example of 
Larambergue (1939), who applied the term 
carrefour to a structure occurring in B. 
contortus, which is similar to that of B. 
tropicus . 

The albumen gland (AL.GL.) is more 
or less kidney- shaped and is slightly con- 
cave on the ventral and convex on the 
dorsal surface. The posterior edge of 
the uterus fits into the hilus of the gland 
while the intestine is lodged in a groove 
(OR) along its posterior edge. The al- 
bumen gland consists of small lobules of 
large, closely packed cells filled with 
deeply staining secretory droplets, simi- 
lar to those found by Wright (1957) in 
the same organ in B. (P.) jousseaumei. 
The duct of this gland is lined by ciliated 
cuboidal cells containing large nuclei. 

The female system 

The oviduct (OD, Figs. 38, 40, 41) is 
convoluted and proximally it is lined by 
a very glandular, columnar, ciliated epi- 
thelium. Its walls are thickest towards 
the uterus. De Azevedo et al. (1957) 
consider the dorsal glandular region of 



the uterus as representing a part of the 
oviduct and designate it as the dilatation 
of the oviduct, although most authors re- 
gard it as part of the uterus. This last- 
mentioned organ is broader proximally 
than distally and lies just below the floor 
of the mantle cavity and, like the albumen 
gland, is slightly concave ventrally and 
convex dorsally. The oviduct which en- 
ters it at the left posterior margin is 
surrounded at its base by an irregular 
sac (S, Fig. 40) extending from the uterus. 
We have not encountered any reference 
to this structure in the literature but an 
apparently similar, though less well de- 
veloped sac, appears to be figured for 
B. contortus by Larambergue (1939) who, 
however, does not refer to it in the text. 
In B. tropicus the penis of the partner 
acting as the male may occasionally be 
found inserted into this sac. A similar 
interpretation is suggested by Laram- 
bergue' s (1939) Fig. 44. In one instance 
we found the penis to have been inserted 
into the spermatheca (Fig. 39). 

Dorsally and running obliquely across 
the posterior surface of the uterus, is 
the large well developed muciparous 
gland (M.GL., Figs. 40, 48). This struc- 
ture consists of tall, large glandular 
cells arranged to form simple acini, the 
openings of which can be seen in regular 
longitudinal rows on the inside of the 
uterus. On the ventral side of the uter- 
us the gland is restricted to the right 
hand posterior region. The cells secrete 
mucus and remain unstained except for 
their nuclei. The rest of the dorsal wall 
of the uterus is folded longitudinally, the 
region along the border of the muciparous 
gland being a darker yellow than the rest 
of the uterus. De Azevedo et aL (1957) 
designate this darker portion as the nida- 
mental gland (N.GL.) while Abdel-Malek 
(1952) and Wright (1957) refer to the 
corresponding structures as the oöthecal 
gland. The longitudinal folds (F) are 
covered with tall, glandular cells with 
almost basally placed nuclei. There are 
large, round, lighter staining areas pre- 
sent probably representing secretory 
cells. The epithelium of this region is 



MORPHOLOGY OF BULINUS TROPICUS 



101 




FIG. 42. The penlal complex; the usually subterminal junction of the vas deferens is obscured by 

the penis sheath. 
FIG. 43. Representative transverse section of the sperm duct. 
FIG. 44. Representative transverse section of the vas deferens. 
FIG. 45. Cross-section of the proximal region of the epiphallus. 
FIG, 46, Transverse section of part of penlal wall, through a papilla, 

FIG. 47. Portion of the wall of the preputium sectioned to show the tissue lining the lumen. 
FIG, 48. Semidiagrammatic cross- section of the uterus to show the structure of the muciparous 

gland, 
FIG. 49. Cross-section of the distal region of the epiphallus. 

See list of abbreviations p. 114 



102 



STIGLINGH, VAN EEDEN AND RYKE 



not richly ciliated. The rest of the uterus 
is also folded but to a lesser degree 
and the ventral surface may be almost 
smooth. The cells in the latter region 
are very tall, bear numerous cilia and 
are interspersed with goblet cells. 

The spermatheca (STH, Fig. 41) is 
round; its size depends on the amount 
of sperm it contains and the age of the 
snail. The spermathecal duct is short 
The walls of the spermatheca are thin 
and covered with a few strands of con- 
nective tissue. On the inside they are 
lined by an epithelium of tall ciliated 
cells with centrally to basally placed 
nuclei. Both the spermathecal duct and 
the vagina are lined by cells of this type 
but, although still ciliated, the cells of 
the latter become more cuboidal toward 
the female aperture. 

The Male System 

The male reproductive system (Figs. 
41, 42) is of more use, taxonomically, 
as it is not subject to such great sea- 
sonal changes as those occurring in the 
female system. The sperm duct (Fig. 
41) arises as a fairly narrow tube and 
is of the same diameter throughout. It 
is lined by a cuboidal ciliated epithelium 
with large nuclei (Fig. 43) and is en- 
sheathed by a thin layer of lightly pig- 
mented connective tissue. 

The prostate gland (PR.GL., Fig. 41) is 
flat ventrally and convex dorsally where 
it abuts against the uterus. The gland 
consists of numerous fingershaped acini 
radiating from a more or less central 
point on its ventral surface. At this 
point the sperm duct enters and the vas 
deferens (V.D.) leaves the gland, thus 
agreeing with the descriptions furnished 
by Larambergue (1939) and Wright (1957) 
for related bulinid snails. Each acinus 
is deep and surrounded by a thin connec- 
tive tissue sheath containing pigment cells 
as described by Wright The simple 
epithelial lining consists of large secre- 
tory cells having large basal nuclei and 
conspicuous nucleoli. In gross dissection 
two zones may be distinguished in the 
gland, viz. a peripheral opaque yellowish 



region, representing the apices of the 
acini, and a central whitish and more 
translucent one, representing the bases 
of the acini. The apical cells are full 
of secretory droplets which readily take 
up acid fuchsin when stained with Mal- 
lory's triple stain. The translucent re- 
gion stains very light blue and the cyto- 
plasm appears to be less granular than in 
the apical cells. They contain large clear 
areas which probably represent masses 
of secretion. A narrow blue staining 
zone intervenes between the peripheral 
and central regions. 

The vas deferens (Fig. 44) is lined by 
a cuboidal ciliated epithelium with large 
nuclei; this lining is surrounded by a 
thick layer of circularly arranged muscle 
fibres interspersed with a few connective 
tissue fibres. 

The penis sheath (P.S., Fig. 42) is 
club-shaped, the proximal end being 
broader. The surface is usually fairly 
smooth although it may be slightly con- 
stricted or even markedly bulging as 
figured by Hubendick (1948). It is thin 
proximally where the lumen is wide and 
conversely it is thick distally where the 
lumen is narrow. The walls of the proxi- 
mal portion consist of a thin muscular 
layer containing scattered pigment cells 
and a few strands of connective tissue 
and are not always of the same thickness 
throughout. At the distal end of the sheath 
where it joins the preputium (PP) the 
outer muscular layers are replaced by 
connective tissue and isolated muscular 
fibres. The preputium is of about the 
same diameter throughout and is straight 
whereas the penis sheath is always bent 
or convoluted. Numerous small muscles 
(EX.M.) are attached along the anterior 
and posterior margins of the preputium. 
According to de Azevedo et al. (1957) 
these are extensor muscles. A single 
large retractor muscle (RE.M.) is in- 
serted at the junction of penis sheath 
and preputium. It has its origin in the 
columellar muscle as far back as the 
base of the uterus. Along the lines of 
attachment of the extensor muscles the 
preputial wall is swollen out into two 



MORPHOLOGY OF BULINUS TROPICUS 



103 



longitudinal pilasters similar to those 
occurring in other species of the Planor- 
bidae, described by Baker (1945),Huben- 
dick (1946, 1955), Mandahl-Barth (1954, 
1956), de Azevedo et al. (1957), Wright 
(1957), and Schutte and van Eeden (1959b). 
Contrary to Hubendick's (1948) statement 
that there are no muscular pillars proxi- 
mally inß. tropicus and Wright's (1957) 
statement that only one of the pilasters 
extends as far as the junction of penis 
sheath and preputium in ß. (P.) jous- 
seaumei, they do in the specimens of 
B. tropicus examined, both extend into 
that region and determine the shape of 
the lumen of the preputium.^ 

In B. tropicus the pilasters are situ- 
ated opposite each other and are almost 
contiguous so that in transverse section 
the lumen isH-shaped. In certain cases, 
however, probably through unequal con- 
traction of the muscles, the pilasters are 
not directly opposite each other and this 
results in an S- shaped lumen. 

The epithelium lining the lumen of the 
preputium, which Hubendick (1948) de- 
scribes as being cuboidal in B. tropicus 
may be regarded as either cuboidal or 
columnar. This was also found to be the 
case in B. (P.) jousseaumei (Wright, 
1957). Whereas the latter author found 
only a few ciliated cells in the preputial 
lining of B. (P.) jousseaumei, and Huben- 
dick (1947) states that the preputium is 
nonciliated in the Planorbidae, the proxi- 
mal region, in B. tropicus, was found to 
be richly ciliated (Fig. 47). The large 
goblet cells of B. (P.) jousseaumei are 
described as grouped together and pene- 
trating into the muscular layer, but B. 
tropicus differs in both these respects 
(G.C., Fig. 47). The differently staining 
cells mentioned by Wright (1957) are 
visible. The epithelium is underlain by 
a distinct basement membrane and the 
rest of the preputial wall consists of a 
loose meshwork of pigmented connective 
and muscular tissue interspersed with 
blood spaces. 



Since the length of the penis sheath 
relative to that of the preputium has been 
employed to characterize certain species 
of the genus Bulinus (Mandahl-Barth 1954, 
1956), we have calculated this ratio for 
a number of specimens of B. tropicus 
(Table EX and Fig. 50). From the table 

TABLE EK. Ratios of the penis sheath to 
the preputium (PS/PP) in each of the sam- 
ples and for snails of different sizes. 



Sample 


n 


Range 


Interval 


Mean 


W 


39 


0.8 - 2.1 


1.3 


1.5 


D 


11 


1.0- 2.0 


1.0 


1.5 


В 


29 


0.9 - 2,3 


1.4 


1.3 


S 


12 


1.0- 1.8 


0.8 


1.3 


К 


10 


1.0 - 1.6 


0.6 


1.3 


A 


10 


1.0 - 1.7 


0.7 


1.4 


H 


8 


1.1 - 2.3 


1.2 


1.2 


M 


8 


1.3 - 2.0 


0.7 


1.6 


G 


10 


1.0 - 1.4 


0.4 


1.3 


^ 7.7 mm 


34 


0.8 - 1.9 


1.1 


1.4 


> 10 mm 


24 


1.0 - 2.3 


1.3 


1.4 



n = number of specimens 

it is apparent that the ratio PS/PP varies 
so much in each of the samples that it 
is impossible to use the ratio obtained 
from a single specimen either as a mea- 
sure to characterize the species, or as 
a criterion to identify the particular spe- 
cimen. The means for the various sam- 
ples dealt with are relatively constant, 
fluctuating between 1.2 and 1.6. More- 
over, from the analysis of the data it 
seems that the ratio does not change with 
age. 

Inside the penis sheath two structures 
may be distinguished, viz., the epiphallus, 
which is a continuation of the vas de- 
ferens, and the penis. This organ opens 
into the preputium as indicated in Fig. 
42. The epiphallus (EP) is a narrow tube 
lined with cuboidal epithelial cells with 
large round nuclei and covered externally 
by a muscular layer (Fig. 45). Histo- 
logically it therefore closely resembles 
the vas deferens except that the develop- 



2According to Demian (1960, see footnote 1) they also so extend in Bulinus truncatus. ED. 



104 



STIGLINGH, VAN EEDEN AND RYKE 



ment of the muscular tissue is weaker 
than in the latter. Distally the epiphallus 
loses its circular appearance owing to 
the accumulation of muscular and connec- 
tive tissue on either side, which produces 
a more or less oval shape. Scattered 
cells full of globules (GLO, Fig. 49) occur 
in this connective tissue. From their 
appearance they seem to be glandular 
cells and, as these globules do not stain 
at all, whereas the other secretions ge- 
nerally take up stains readily, they are 
probably mucous cells. The cells lining 
the lumen of the epiphallus in this region 
are taller than elsewhere and the nuclei 
are basally placed. The epiphallus usually 
joins the penis subterminally. Neither 
this duct nor the penis proper contains 
any pigment cells. 

The morphological and histological de- 
tails of the walls of the penis are depicted 
in Fig. 46. From this illustration, it is 
apparent that the wall of the penis con- 
sists of two layers, viz. an inner epi- 
thelial layer and an outer layer consisting 
of connective and muscular tissue. The 
latter forms a series of projections (PAP) 
directed toward the lumen and clothed 
with greatly elongated epithelial cells, 



thus forming protuberances projecting 
into the lumen. Following Larambergue 
(1939), we refer to these protuberances 
as papillae. In surface view the arrange- 
ment of these papillae resembles that of 
the protuberances of a pineapple. Proxi- 
mally they are large while the muscular 
part of the walls of the penis is not thick. 
Distally the papillae decrease in size and 
the cells become more squat while the 
muscular layer increases in thickness. 
The large vacuolated cells described by 
Larambergue (1959) occur in the distal 
region. At its extreme tip the penis it- 
self becomes thin-walled and the epithe- 
lial cells cuboidal. In most cases a short 
ridge occurs on the inside of the penis in 
line with the opening of the epiphallus. 
This ridge coincides with a groove on 
the external surface. In those cases in 
which the ridge is absent its position is 
generally betrayed by a slight concen- 
tration of longitudinal muscle fibres. To 
our knowledge no ridge of this kind has 
as yet been described for any of the 
bulinids. In a few instances the penis 
and sheath could not be distinguished 
and the lumen of the sheath was filled 
with loose, strongly pigmented connective 





3-0 



FIG. 50. Histogram of the length ratioof the penis sheath to the preputium (PS/PP); 155 specimens 
measured. 

FIG. 51. Histogram of the length ratio of the penis to the epiphallus (P/EP); 147 specimens meas- 
ured. 



MORPHOLOGY OF BULINUS TROPICUS 



105 



tissue. As in the case of the ratio penis 
sheath to preputium, (PS/PP, Table IX 
and Fig. 50) the ratio penis to epiphallus 
(P/EP, Table X) is very variable. In 



TABLE X. Ratios of the penis to epiphallus 

(P/EP) for each of the samples and for 

snails of different sizes. 



Sample 


n 


Range 


Interval 


Mean 


W 


37 


1.0- 2.8 


1.8 


1.4 


D 


10 


1.2 - 2.2 


1.0 


1.5 


В 


25 


0.9 - 2.1 


1.2 


1.3 


S 


12 


0.9 - 1.5 


0.6 


1.2 


К 


10 


0.9 - 1.3 


0.4 


1.1 


A 


10 


0.8 - 1.6 


0.8 


1.0 


H 


8 


0,9 - 2.3 


1.4 


1.2 


M 


8 


0.9 - 1.4 


0.5 


1.4 


G 


10 


1.0 - 2.1 


1.1 


1.4 


L 7.7 mm 


28 


0.9 - 2.8 


1.9 


1.3 


> 10 mm 


21 


0.9 - 2.2 


1.3 


1.4 



n = number oí specimens 

the various samples this last mentioned 
ratio varies between 0.8 and 2.4, whereas 
the means of the different samples vary 
between 1.0 and 1.5. In spite of the ap- 
parently much greater variation than that 
found in the case of the ratio PS/PP, 
Fig. 51 reveals that most of the values 
of P/EP are concentrated around 1.3 and 
1.4 and comparison with Fig. 50 shows 
that there is a more normal distribution 
of the values than in the case of the ratio 
PS/PP. 



ACKNOWLEDGEMENTS 

We wish to express our gratitude to 
Mr. A. Bisschoff for the photography and 
to the S. A. Council for Scientific and 
Industrial Research for financial assis- 
tance received. 



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MORPHOLOGY OF BULINUS TROPICUS 



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ZUSAMMENFASSUNG 

BEITRAG ZUR MORPHOLOGIE VON BULINUS TROPICUS 
(GASTROPODA: BASOMMATOPHORA: PLANORBIDAE) 



Gegenstand der vorliegenden Studie ist Bulinus (Bidinus) tropicus (Krauss), 
eine mit den Zwischenwirten der Schistosome der haematobium- Gruppe eng ver- 
wandte afrikanische Süsswasserschnecke, die auch als Überträger der Trematoden 
Paramphistomum und Cotylophoron von veterinärer Bedeutung ist. Drei taxonomisch 
kennzeichnenden Partien, dem Gehäuse, der Radula und dem Penialkomplex, wurde 
besondere Aufmerksamkeit geschenkt; andere Organe wurden jedoch gleichfalls 
morphologisch und histologisch untersucht. 

Das zur Untersuchung dienende Schneckenmateral wurde sowohl auf Ähnlichkeit 
mit typischen B. tropicus Exemplaren hin gesammelt, wie auch in Hinblick auf seine 
Herkunft aus der Gegend des locus typicus. Trotz dieser sorgfältigen Auswahl wurde 
aber hier wieder einmal der notorische Polimorphismus dieser Art bestätig. Die 
wichtige Rolle der Umweltseinflüsse in der Bildung von Schalentypen welche sich 
sowohl ihrer Gestalt nach, wie auch ihrer Beschaffenheit nach, von einander unter- 
scheiden, wird erörtert. Obwohl sich unter unserem Material bei ausgewachsenen 
Formen 2 Haupttypen vorfanden, ein langgestreckter, eng genabelter mit fliessendem 
Wasser verbundener und ein gedrungener, weit genabelter, mit stehendem Wasser 
verbundener (Fig. 3), gehörten die jugendlichen Formen einem einzigen Typus an, 
ein Hinweis darauf, dass, wie es auch bereits Schutte und van Eeden (1959a) für 
Biomphalaria pfeifferi hervorgehoben haben, die Gestalt der jugendlichen Exemplare 
weniger von der Umgebung abhängig ist als die der Erwachsenen. Dieses scheint 
insofern folgerichtig als ja die letzteren den modifizierenden Einflüssen der Umwelt 
länger ausgesetzt waren als die Jungschnecken. Konchologische Messungen wurden 
an insgesamt 171 Schnecken aus 9 Fundorten vorgenommen, wobie die Länge 
imd Breite des Gehäuses, Länge und Breite der Schalenmündung, und Länge 
des Gewindes gemessen, sowie die verschiedenen Grössenverhältnisse dieser 
Ausmasse zueinander berechnet wurden, um die Natur der Beziehungen zwischen 
immer je zwei derselben zu erforschen. Die Gewinde- und Lippenabfallswinkel 
wurden ebenfalls gemessen. Nur ein Vergleich mit bei anderen Arten erhaltenen 



108 STIGLINGH, VAN EEDEN AND RYKE 

Werten dieser selben Messui^en wird zeigen, welche dieser Beziehungen sich als 
genügend ausgeprägt erweisen werden um taxonomisch verwertbar zu sein. Obwohl 
die einzelnen Messungen manchmal stark variieren, so sind doch die mittleren Werte 
für jede der 9 Proben im allgemeinen ziemlich konstant. Eine Ausnahme bildet nur 
das Längenverhältnis Gehäuse/ Gewinde, in welchem die mittleren Werte zwischen 
6,7 und 15.2 schwanken. Dennoch war das Gewinde in kleineren Formen immer 
verhältnismässig kürzer als in den grösseren. Der apikale Winkel des Gewindes 
zeigte sich ausserordentlich veränderlich: 58 ° - 134° . Der Mttelwert der Mün- 
dungslippenabfallswinkel hlnggen liegt für alle Posten bei 57° order 58 ° , ausser in 
einem einzigen, wo er 61° betragt. In Bezug auf die Mündungsform zerfallen die 
ausgwachsenen Gehäuse gewöhnlich ebenfalls in 2 Hauptgruppen: deren Gestalt 
scheint nlch nur vom Alter abhängig zur sein sondern auch von verschiedenartigen 
ökologischen Bedingungen. Obwohl die Gestaltung der Kolumellapartie innerhalb 
der Fimdortsproben ziemlich einheitlich war, so erscheint sie doch von Gruppe zu 
Gruppe etwas verändert. 

Ein Osphradium wurde ausserhalb der Mantelhöhle auf dem Mantelwulst ge- 
funden. Die Kieme (Pseudobranchie) erwies wich als normal. Die Analregion 
hingegen war etwas anders als im Schrifttum beschrieben, nämlich mit schmälerem 
Anallappen und ausgesprochenerer Rektalleiste. Die Mittelwerte der Längenver- 
hältnisse Niere/ Ureter schwankten zwischen 2.0 und 4.6. 

An der Decke der Mantelhöhle befinden sich nur 2 der in den Planorbiden 
taxonomisch bedeutsamen Falten: es fehlen die Nierenleiste und die mittlere Rek- 
talleiste. Die zwischen Niere und Rektum beûndliche intermediäre Mantelleiste 
unterscheidet sich von der von Mandahl- Barth (1956) veröffentlichten Abbildung 
durch ihre grössere Länge und dadurch, dass sie immer nach rückwärts bis zum 
Rand der Mantelhöle reicht, wo sie der seitlichen Rektalleiste begegnet. 

Eine Beschreibung der die Pseudobranchie entleerenden Blutgefässe ist gegeben. 
Die sphärischen, von Schutte und van Eeden (1959b) im Pericardraum der afrikani- 
schen planorbiden Schnecke Bio»iphaIaria pfeifferi angetroffenen Körper wurden in 
einer grösseren Anzahl von Bulinus tropicus ebenfalls aufgefunden. Es handelt sich 
möglicherweise um die Eier eines nicht identifizierten Wesens. 

Im Verdauungstrakt entsprach der Idefer, im Gegensatz zu gewissen im Schrift- 
tum gemachten Angaben, durchaus dem normalen Schema für Bulinus. Unter- 
suchungen über die allgemeinen Proportionen der Radula zeigten, dass das Verhält- 
nis der Länge zur Breite ziemlich konstant ist (2.4 - 2.6) und dass sich somit die 
mittleren Verhältniszahlen möglicherweise zu Vergleichen mit verwandten Arten 
eignen könnten. Die Seitenränder der Zahnplatten waren gewellt. Kleine Zäckchen 
wurden zwischen den Zacken des Mittelzahnes und auch an der Basis des Mesokonus 
der Seitenzähne gefunden. Dieser letztere ist beinahe nie einfach dreieckig, wie 
von Mandahl- Barth (1956) als kennzeichnend fur die B. tropicus Gruppe angegeben; 
manchmal nähert er sich sogar der Pfeilspitzenform die ihm zunach fur die B, trun- 
catus Gruppe charakteristisch ist. Trotz der Begrenzungen die anerkannterweise den 
Radulaformeln inneliegen, word hier eine allgemeine Formel für B. tropicus, wie 
folgt, angegeben: 1 : 6+2 : 24 x 123. 

Die verschiedenen Bezeichnungen der Ganglien des Nervenschlundrings werden 
erörtert und die daraus entspringendem Nerven beschrieben. Die Speicheldrüse 
geht auch hier durch den Nervenring hindurch. 

Die Zwitterdrüse ist nicht in männliche und weibliche Zonen gegliedert. Wie 
auch bei gewissen anderen Lungenschnecken weisen die Oozyten doppelte Zellkerne 
auf. Die "carrefour" Gegend unterscheidet sich von der bei der nordamerikanischen 
planorbiden Schnecke Helisonm trivolvis beschriebenen, stimmt jedoch mit der 
bei BiotHplialarin pfeifferi gefundenen überein. Die Anwesenheit eines unregel- 
mässign, vom Uterus ausgehenden Sackes, welcher teilweise die Basis des Eileiters 
umfasst, wird hervorgehoben. In der Prostata lässt sich eine opake, perlpherale, 
gelbliche Zone von einer durchscheinenderen, weisslichen, zentralen, unterscheiden. 
Im proximalen Teil des Penis wurde die Anwesenheit einer kurzen inneren Leiste 
bemerkt. Die Pfeiler im Präputium erstrecken sich bis zu seiner Vereinigung mit 
der Penisscheide, Das Längenverhältnis Penlsscheide/Präputium schwankt zwar im 
einzelnen sehr, aber die Mittelwerte für die verschiedenen Gruppen variieren nur 
zwischen 1,2 und 1,6, 



I 



MORPHOLOGY OF BULINUS TROPICUS 109 

RESUME 

CONTRIBUTIONS A LA MORPHOLOGIE DE BULINUS TROPICUS 
(GASTROPODA: BASOMMATOPHORA: PLANORBIDAE) 

L'étude porte sur Bidinus (Bulinus) tropicus (Krauss) un mollusque fluviatile 
africain prochement apparenté aux hôtes intermédiaires des schistosomes du 
groupe haeniatobiii))!, qui a aussi une certaine importance vétérinaire comme vecteur 
des trematodes Para»iphisto»m}}i etCotylophoron. Notre attention a été spécialement 
dirigée sur 3 charactères d'importance taxonomique: la coquille, la radule et le 
complexe pénial; cependant, les autres organes furent également examinés, mor- 
phologiquement ainsi qu'histologiquement. 

Dans la sélection du matériel pour cette étude la ressemblance de ces mollus- 
ques aux spécimens typiques de B. tropicus ainsi que leur provenance de la region 
approximative du lieu typique furent prises en considération. Malgré ce choix, la 
présente étude de ces coquilles a démontré une fois de plus le polimorphisme notoire 
de l'espèce. Le rôle important des facteurs écologiques dans la formation de types 
conchologiques assez divergeants, différant en forme ainsi qu'en sculpture, est 
discuté. Quoique 2 types principaux peuvent être distingués dans notre matériel, 
l'un élongé, à ombilic étroit, associé à l'eau courante et l'autre trapu, à ombilic plus 
large, associé aux mares (Fig. 3), il n'y avait qu'un seul type juvénile, fait qui 
suggère, comme l'ont déjà observé Schutte et van Eeden (1959a) pour Biomphalaria 
pfeifferi, que les formes jeunes sont moins affectées par l'ambiance que ne le sont 
les adultes, ce qui est d'autant plus logique que les derniers sont exposés aux in- 
fluences modifiantes plus longtemps que les premiers. Une analyse conchologique 
fut faite sur 171 exemplaires provenant de 9 localités différentes. Furent mesurés: 
longueur et largeur de la coquille et de 1' aperture, ainsi que hauteur des tours 
de spire. Les divers rapports, l'un à l'autre, de ces mesures furent calculés afin 
de découvrir la nature de leurs relations mutuelles. Les angles de la spire et de 
la dépression lábrale furent également mesurés. Ce n'est pourtant que la com- 
paraison de ces rapports avec les valeurs correspondantes dans les espèces 
proches qui montrera lesquels sont suffisamment distincts pour servir taxonomi- 
quement. Quoique les écarts individuels de ces quotients sont parfois consi- 
dérables, les moyennes obtenues pour les 9 lots sont d'habitude assez constantes, 
exception faite du rapport entre les longueurs des coquilles et des spires, où ces 
moyennes varient entre 6.7 et 15.2. Néanmoins les spires étaient toujours relative- 
ment plus courtes dans les petits specimens que dans les grands. L'angle apical de 
la spire est très variable: 58° - 134°. L'angle moyen de dépression de la lèvre 
aperturale mesurait 57*^ et 58° pour toutes les localities sauf une, où il était 61° . 
Quant à la forme de Г aperture, les coquilles adultes appartenaient d'habitude à 2 
groupes; ce caractère semble changer non seulement avec l'âge mais aussi avec 
les diverses conditions écologiques. La région columellaire était assez uniforme 
dans chacun des lots, mais varie d'un groupe à l'autre. 

L'osphrade fut trouvé à l'extérieur de la cavité palléale sur le collier du man- 
teau. La pseudobranchie est normale. La région anale diffère légèrement de cer- 
taines descriptions antérieures en ayant un lobe anal plus étroit et une arête rectale 
plus distincte. Les valeurs moyennes du rapport rein/urètre varient entre 2.0 et 
4.6 dans les lots différents. 

Seulement 2 des plis taxonomiquement importants dans les planorbes se 
trouvent sur la paroi supérieure de la cavité palléale tandis que le pli rénal et le 
pli rectal central manquent. Le pli palléal intermédiaire, situé sur le manteau 
même entre le rein et le rectum, se distingue de l'illustration donnée par Mandahl- 
Barth (1956) par sa plus grande longueur et du fait qu'il s'étend toujours postérieure- 
ment jusquau bord du manteu où il rejoint le pli rectal. 

Les vaisseaux sanguins évacuant la pseudobranchie sont décrits. Les objects 
sphériques, déjà observés par Schutte et van Eeden (1959b) dans la cavité péri- 
cardiale de Biomphalaria pfeifferi, furent également trouvés dans un grand nombre 
d'individus de B. tropicus. Il est possible qu'ils soient les oeufs d'un organisme 
inconnu. 

Dans le système digestif, la mâchoire fut trouvée être différente des descrip- 
tions présentées dans la literature et conforme au dessin général pour les bulins. 
Une étude des proportions générales de la radule révèle que la moyenne du rapport 



lio STIGLINGH, VAN EEDEN AND RYKE 

longueur sur largeur est assez constante (2.4 à 4.6) et que ce rapport pourrait ainsi 
se montrer utile à comparer les espèces voisines. Les bords des dents sont ondulés. 
De petits denticules furent découverts entre les cúspides des dents centrales et à 
la base du mésocone des dents latérales. Les mésocones ne sont presque jamais 
simplement triangulaires, condition typique pour le groupe de B. tropicus selon 
Mandahl- Barth (1956), et s'approchent même en certain cas, de la forme en pointe 
de flèche caractéristique, selon cet auteur, pour le groupe de B. triincatus. Malgré 
les limitations reconnues de toute formule radulaire, une formule généralisée est 
présentée pour la radule de B. tropicus: 1 : 6 + 2 : 24 x 123. 

Les noms donnés aux divers ganglions de l'anneau circumésophagéal sont dis- 
cutés et les nerfs y prenant origine sont décrits. Les glandes salivaires passent à 
travers de cet anneau. 

Dans la glande hermaphrodite il n'y a pas de division entre zones maie et 
femelle. Les oocytes, comme dans certains autres pulmones, ont des nucléoles 
doubles. La région du "carrefour" diffère de celle décrite pour le planorbe Helisoma 
trivolvis de l'amérique du nord et conforme avec les conditions trouvées dans le 
planorbe africain Bioniphalaria pfeifferi. La présence d'un sac irregulier provenant 
de l'utérus et entourant partiellement la base de Г oviduct est relevée. Dans la 
glande prostate deux régions principales peuvent être distinguées, l'une péri- 
phérique opaque et jaunâtre, l'autre centrale, plus pellucide et blanchâtre. La 
présence d'une arête intérieure et courte dans la région proximale du pêne est 
signalée. Les pilastres du prépuce s'étendent jusqu'à la jonction de ce dernier avec 
la gaine péniale. Le rapport gaine péniale/prépuce varie considérablement, mais 
les moyennes pour les divers groupes ne varient qu'entre 1.2 et 1.6. 



CONTRIBUCIÓN AL ESTUDIO DE BULINUS TROPICUS 
(GASTROPODA: BASOMMATOPHORA: PLANORBIDAE) 

RESEÑA 

Estudio realizado sobre el Bulinus tropicus (Krauss), caracol dulceacuícola 
africano que está estrechamente relacionado al huésped intermediario de los 
esquistosomas del grupo hematobium, y que tiene también importancia veterinaria, 
como trasmisor de los trematodes Paramphistomun y Cotylophoron. Se prestó 
especial atención a 3 caracteres taxonómicos: la conchilla, radula y complejo 
penial. Los otros sistemas fueron también examinados morfológica e histológi- 
camente. 

Las muestras del caracol fueron seleccionadas en base a su parecido a los 
especímenes típicos de B. tropicus y a su distribución geográfica, en la región de 
la localidad típica. A pesar de la prolijidad en la selección, el estudio concho- 
lógico destaca una vez más el notable polimorfismo de la especie. Se discute la 
importancia de los factores ecológicos en el desarrollo ampliamente divergente de 
los tipos de concha en forma y textura. Aún cuando se encuentran 2 formas adultas, 
una prolongada, estrechamente umbilicada y asociada con cursos de agua, y otra de 
forma ampliamente umbilicada asociada con lagunas y aguas estancadas (fig. 3), 
existe solamente un tipo principal juvenil sugiriendo, tal como fuera observado por 
Schutte y Van Eeden (1959a) para la Biomphalaria pfeifferi que el tipo juvenil es 
menos afectado por el ambiente que el adulto, lo que parecería lógico, ya que el 
último mencionado ha estado expuesto a las únfluencias modificantes por un período 
más largo que los jóvenes. Un análisis conchométrico se llevó a cabo en el largo, 
ancho, y alto - ancho de la abertura, y largo de la espira, en 171 caracoles de 9 
localidades. Se calcularon diferentes proporciones de modo de descubrir la 
naturaleza de la relación en cualquiera de estas características. Los ángulos 
espirales y depresión del labio también fueron medidos. La comparación con 
valores correspondientes de otras especies podrán indicar cuales, de todas las 
proporciones obtenidas, varían suficientemente para usarlas taxonómicamente. 
Los límites de estos valores son grandes en algunos casos y la media de las 9 
muestras es bastante constante. Una excepción es la comparación entre la longitud 
total de la concha y la de la espiral, en la cual los valores de la media varían entre 



MORPHOLOGY OF BULESfUS TROPICUS HI 

6,7 y 15,2. Sin embargo se descubrió que la media espiral es relativamente más 
corta en los ejemplares pequeños. El ángulo apical es muy variable: 58-134? La 
media del ángulo de la depesiön del labio es 57-58°para todos los ejemplares, con 
excepción de uno solo, 61" Con respecto a la configuración de la abertura, los 
adultos se clasifican por lo general en dos grupos principales. Tal característica 
parece variar no solamente con la edad del ejemplar, sino también con las con- 
diciones ecológicas. Aunque la región de la columnilla es bastante uniforme en 
cada muestra, varía de uno a otro ejemplar. 

El osfradio se encuentra fuera de la cavidad del manto, en el cuello. La 
branquia (pseudobranquia) es normal. La región anal se diferencia ligeramente de 
las descripciones previas en que el lóbulo anal parece ser más estrecho y la 
arruga renal más clara. La longitud reñón-uretra varía entre valores de la media 
de 2,0 y 4,6 en los distintos ejemplares. 

Sólo dos de las arrugas taxonómicamente importantes se presentan en la parte 
superior de la cavidad paleal. Las arrugas renal y media rectal no se encuentran. 
La arruga intermedia de la cavidad, entre el riñon y el recto se diferencia de la 
figura de Mandahl- Barth (1956) en que es más larga y siempre se extiende poste- 
riormente hasta encontrar la arruga lateral rectal al borde de la cavidad paleal. 
Se mencionan las venas en que desagotan las branquias (pseudobranquias). Los 
cuerpos esféricos mecionados por Schutte y Van Eeden (1959b) para la cavidad 
pericardial de B. pfeifferi, se encontraron en gran número de especímenes; se 
cree que sean los huevos de organismos no identificados. 

En el sistema digestivo, la mandíbula parece diferir de las descripciones 
ofrecidas en la literatura y concuerda a la organización general de Bulinus. El 
estudio general de las proporciones radulares demuestra que el porcentaje de la 
media largo/ancho es muy constante (2,4 - 2,6), de manera que este porcentaje 
puede ser muy útil en la comparación con las especies mencionadas. Los lados de 
los dientes son acanalados y aparecen pequeños dentículos entre los centrales y 
en la base del mesocono de los laterales; este último casi nunca es simplemente 
triangular como estableció Mandahl-Barth (1956) para el grupo de B. tropicus. En 
ciertos casos se aproxima a la característica forma en punta de flecha del grupo 
de B. truncatus. A pesar de las limitaciones que se conoce en la fórmula radular, 
una fórmula generalizada puede ofrecerse para B. tropicus: 1:6+2:24x123, 

Los nombres aplicados a los varios ganglios del anillo circumesofageo son 
discutidos, asi como también la descripción de los nervios que de él se originan. 
Las glándulas salivares pasan a través del nervio del anillo. 

En la glándula hermafrodita no hay división de zona masculina y femenina. 
Los oocitos tienen doble nucelolo como en el caso de ciertos otros pulmonados. La 
región "carrefour" difiere de la definida para el planorbido norteamericano 
Helisoma trivolvis y concuerada con la condición encontrada en el africano B. 
pfeifferi. Llama la atención un saco irregular que se extiende desde el útero y que 
rodea parcialmente la base del oviducto. En la próstata se distinguen dos regiones 
principales, una periferial opaca de color amerillento, y otra mas traslucida, blan- 
quecina. Se nota la presencia de una arruga interna corta, en la proximidad del 
pene. Las pilastras del prepucio se extienden hasta la unión del pene con la capa 
que envuelve as mismo. El porcentaje de la capa que envuelve al pene-prepucio varia 
considerablemente, pero las medidas de los ejemplares analizados separadamente 
varían sólo entre 1,2 y 1,6. 



112 STIGLINGH, VAN EEDEN AND RYKE 

К ИЗУЧЕНИЮ МОРФОЛОГИИ BULINUS (BULINUS) TROPICUS (KRAUSS) 
(MOLLUSCA BASOMMATOPHORA PLANORBffiAE) 

Айна Стиглинг, Д. А. ван Идеи и П. А. Д. Райк 

Реэюие 

Проведено исследование Bulinus (В.) tropicus IKrauss) 
моллюска семейства Planorbidae, вида близко родственного про- 
межуточным хозяевам S сйг« íosowa группыАае wa ¿оЬгмги в Африке и 
имеющего, кроме того, ветеринарное значение, как промежуточный 
хозякнРагагпркгз tomum . Особое внимание уделено трем важнейшим 
для систематики частям--раковине, радуле и. копулятивному аппа- 
рату, однако, и другие системы органов исследованы как морфо- 
логически, так и гистологически. 

Сборы моллюсков были разобраны по их сходству с типичными 
экземплярами В. tropicus и по их географическому распростране- 
нию. Несмотря на эту предварительную разборку, изучение рако- 
вин еще раз показало значительную полиморфность этого вида. 
Обнаружено несколько типов раковин, различакщихся как по обли- 
ку так и по скульптуре; эти типы рассматриваются, как экологи- 
ческие варианты. Хотя ö материале выявлены 2 типа раковин 
взрослых ос о б ей- -удлиненные, с узким пупком, обычно, гладкие 
раковины из проточных водоемов и укороченные, с широким пупком, 
обычно, ребристые раковины из прудов (табл. 3), --молодь одно- 
типна, что согласуется с данными Шютте и ван Идена (1959а) для 
Biomphalaria pfeifferi свидетельствующими, что форма молодых 
особей меньше зависит от внешних условий, чем форма взрослых. 
Это по-видимому понятно, так как последние подвергаются воз- 
действию внешних факторов более длительный период. Биометри- 
ческий анализ раковин показал, что характер завитка сильно ва- 
рьирует, как по величине апикального угла, так и по отношению 
высоты завитка к общей высоте раковины. У мелких форм завиток 
относительно короче. По форме устья взрослые особи, обычно, 
разделяются на две основные группы. Этот признак по-видимому 
изменяется не только с возрастом, но и при разных экологических 
условиях. Область столбика, хотя и однородна в пределах сбора, 
но и она варьирует от популяции к популяции. 

Как установлено, осфрадий помещается вне мантийной полости 
на ее передней стенке. Адаптивная жабра обычной формы, но 
анальная область несколько отличается от того, что было описано 
предыдущими авторами. Отношение длин почки и мочеточника 
варьирует от 2,0 до hth-- 

На крыше мантийной полости имеются только два системати- 
чески важных мышечных грвбня--ренальный и средний ректальный 
гребни отсутствуют. Промежуточные мантийные гребни расположе- 
ны не так, как на рисунке, приведенном Мандал-Бартом (19Ç6); 
Они длиннее и всегда продлены назад, где встречаются с лате- 
ральным ректальным гребнем и краем мантийной полости. Приве- 
дено описалие кровеносных сосудов, снабжающих адаптивную жабру. 
Сферические тельца, отмеченные Шютте и ван Иденом (19С9в) в 
перикардии Biomphalaria pfeifferi найдены и у многих экземпляр- 
ов Bulinus tropf cus. Они, возможно, являются яйцами какого-то 
организма. 

Челюсть построена по тому же типу, как и у других Bulinus 
и отличается от описанной в литературе. Изучение общих пропор- 
ций радулы показало, что отношение ее длины к ширине сравнитель- 
но постоянно (2,Í4. - 2,6) и это отношение может быть использовано 
при сопоставлении с близкими видами. Установлено, что стороны 
зубов желобчатые. Между зубцами центрального зуба и при осно- 
вании мезокона латеральных обнаружены мелкие зубчики. Мезокон 
латеральных зубов никогда не бывает просто треугольным, как это 
было описано Мандал-Бартом (195^) для группы tropicus рода Bul i- 



MORPHOLOGY OF BULINUS TROPICUS 113 

nus и в некоторых случаях форма этого зубца приближается к за- 
остренной, характерной для группы truncatus . Несмотря на извест- 
ную ограниченность радулярной формулы, предлагается обобщенная 
формула для В. tropicus 1:6 + 2 ; 2Í4. х 123. 

Обсуждаются названия различных ганглиев околопищеводного 
кольца и описываются отходящие от этих ганглиев нервы. Слюнные 
железы проходят сквозь нервное кольцо. 

В гермафродитной железе нет разделения на мужскую и женскую 
зоны. Ооциты, как установлено имеют подобно некоторым другим 
Pulmón at а двойные нуклеоли. Характер области квадривия отлича- 
ется от картины, наблюдаемой у Bulinus (Phy sopsis) jous seaumei 
и североамериканской Helisoma trivolvis и соответствует тому, 
что обнаружено у Biomphalaria pfeifferi. Особое внимание обра- 
щается на неправильный мешок, отходящий от матки и частично 
окружающий основание яйцевода. В простате выделяются два основ- 
ных участка: периферический--мутный желтоватый и центральный-- 
более прозрачный беловатый. В проксимальной части пениса обна- 
ружен короткий внутренний гребень. Пилястры препуциума начина- 
ются от места соединения последнего с мешком пениса. Отношение 
длин мешка пениса и препуциума сильно варьирует, однако, сред- 
ние величины этого отношения у разных популяций находятся в 
пределах 1,2 - 1,6, 



114 



STIGLINGH, VAN EEDEN AND RYKE 



LIST OF ABBREVIATIONS 



A - auricle 

AC - acinus 

AL.GL. - albumen gland 

AL.GL.D. - albumen gland duct 

A.L. - anal lobe 

АО - aorta 

В - base 

B.C. - basal or Sertoli cells 

B.C. - buccal ganglion 

BL - blood 

B.M. - basement membrane 

B.RET. - buccal retractor 

B.R.N. - buccal retractor nerve 

BU.M. - buccal mass 

B.W. - body wall 

B.W.N. - body wall nerve 

С - central cavity 

C.A. - common atrivim 

CAE - caecum 

CAP - capsule 

CAR - carrefour 

С. В. С. - cerebro-buccal connective 

CG. - cerebral ganglion 

CIL. С. - ciliated cells round aperture of 

osphradium 
C.N'. - CQllar nerve from right parietal 

ganglion 
C.N". - collar nerve from visceral ganglion 
COL - collar 
CR - crown 
CRY - crystals 
C.T. - connective tissue 
D - denticle 

D.T.P. - dorsal tentacular process 
E - epithelium 
EC - ectocone 
EG - eggs 

EM.C. - large embryonic cells 
EN - endocone 
EP - epi phallus 
EX.M. - extensor muscles 
EYE - eye 
F - fluted edge 
FO - fold 
FOO - foot 
G - gill 

GAN - ganglion 
G.C. - goblet cells 
GLC. - giant cells 
GLO - globules 
G.N. - gill nerve 

GR - groove accommodating intestine 
H.D. - hermaphrodite duct 
H.GL. - hermaphrodite gland 
LC.L. - inferior cerebral lobe 
I.M.R. - intermediate mantle ridge 
INT - intestine 
J - jaw 
К - kidney 

LAT. N. - lateral nerves 
L.J. - lateral jaws 
L.N. - labial nerve 
L.R.R. - lateral rectal ridge 
L.UT. - lumen of uterus 
MA - mantle 



M.C.F. - mantle cavity floor 

M.C.L. - muscular and connective tissue layer 

M.C.R. - mantle cavity roof 

ME - mesocone 

M.N. - nerves supplying muscles 

M.GL. - muciparous gland 

M.S. - muscle strands 

MU. L. - muscular layer 

N - nucleus 

N.C. - nurse cell 

N.GL. - nidamental gland 

N1 - nucleoli 

О - osphradium 

ОС - oocytes 

OD - oviduct 

OE - oesophagus 

O.N. - oesophageal nerve 

OS.N. - osphradial nerve 

OV - egg 

PA.G. - parietal ganglion 

PAP - papilla 

P.C. - peripheral cavity 

P. COL. - posterior part of collar 

PE.G. - pedal ganglion 

PE.N. - pedal nerve 

PER - pericardium 

P.F. - primary fold 

PLC. - pigment cell 

PL.G. - pleural ganglion 

PN - pneumostome 

PN.N - pneumostome nerve 

PP - preputium 

PR.GL. - prostate gland 

P.S. - penis sheath 

P.V. - pulmonary vein 

R - rectum 

RE.M. - retractor muscle 

R.SH. - radula sheath 

R.SH.N. - radula sheath nerve 

R.V. - renal vein 

S - sac 

SAL. GL. - salivary gland 

S.B. - sperm bundle 

S.F. - secondary folds 

SG - spermatogonia 

S.K. - saccular part of kidney 

S.N. - siphon nerve 

SP - sperm 

ST - statocyst 

STD - spermatids 

STOM - stomach 

STH - spermatheca 

T - tentacle 

Т.К. - tubular part of kidney 

T.N. - tentacular nerve 

и - ureter 

U.C. - urine concretion 

U.N. - uterine nerve 

V - ventricle 

VA - vagina 

V.C. - vacuolated cells 

V.D. - vas deferens 

V.G. - visceral ganglion 

V.S. - vesiculae seminales 

V.T. P. - ventral tentacular process 



МА1АСОЮС1А, 1962, 1(1): 115-137 



PUNCTATION OF THE EMBRYONIC SHELL OF 

BULININAE (PLANORBroAE) AND SOME OTHER BASOMMATOPHORA 

AND ITS POSSIBLE TAXONOMIC-PHYLOGENETIC IMPLICATIONS! 

H. J. Walter 
Liberian Institute of the American Foundation for 
Tropical Medicine, Inc. , Harbel, Liberias 

ABSTRACT 

Microscopic punctation of the embryonic shell is here reported for the first 
time to be a character universal in Bulinus s.l. over its geographic range, and to 
exist in the only other recognized genus of Bulininae, Indoplanorbis. 

The author studied over 1,500 Bulinus s.l. shells of at least 14 species, "sub- 
species," or varieties of the subgenera Bulinus s.s, , Pyrgophysa and Physopsis; 
these were represented by 106 different field and laboratory populations, particu- 
larly from Liberia, but also from Sardinia and Iraq and from numerous other lo- 
calities ranging through the length of Africa. Punctation was observed in every 
specimen studied except in relatively few cases when damage to the shell or other 
factors interfered. The punctae are well-defined pits consistently occurring in a 
basic pattern that dominates the embryonic microsculpture and differs somewhat 
for the 3 subgenera. Study of large numbers of shells of embryonic laboratory 
reared snails provided basic information about the nature and arrangement of the 
punctae and of other microsculptural elements and showed the constancy of punc- 
tation in each of the 3 subgenerlc groups oi Bulinus. Apical punctation of the shell 
has been reported by others for each of these subgenera, but only for a very few 
species and pertinent previous literature suggests that even in these, some indi- 
viduals or populations fall to develop the character. The commonly Inexact usage 
of terms such as "dots," "nodules," "punctures" or "Impressions," along with 
meagre data in past conchologlcal descriptions, show that in respect to micro- 
sculpture, the species of Bulininae are yet poorly known, the same applying for the 
Basommatophora In general. Punctation must have been overlooked In the past be- 
cause it Is identifiable only In relatively undamaged, very clean shells, with ap- 
propriate magnifications and critical illumination. Success In demonstrating puncta- 
tion depended greatly on the author's technique of cleaning shells with sodium hypo- 
chlorite, which permitted study of sculptural detail by transmitted light. 

Among non-bulinlne Planorbidae embryonic punctation had been previously 
known to occur in the "Se^menizwö -group" and in Platytaphius ('i=Taphius) and, in 
other Basommatophora, in the "ancylid" Bumupia of Africa, and in the ellobilds 
Melampus , Phytia, and Pythia. Here, from the examination of a few species of non- 
bulinlne planorblds, the author reports the existence of nuclear punctation in 
Planorbarius corneus and its total lack in Planorbina (Australorbis and Biomr 
phalario) and in a species of Gyraulus. The same absence of punctation was found 
In various Lymnaeidae, In Physa and in Ferrissia. 

Among the Basommatophora, apical microsculpture has been accepted as of 
taxonomic value within the Ancylidae, but otherwise its possible taxonomic- 
phylogenetic significance in relation to taxa of all levels within the order has 
so far been given only the slightest attention. The author here raises some ques- 
tions about phylogenetic possibilities within the order in relation to punctation. 
As for group-relationships within the Planorbidae, It is considered that, on the 
basis of known anatomical characters, the Bulininae, the palearctlc Planorbarius, 
the nearctlc Helisoma and the neotropical Taphius andecolus are all mutually re- 
lated in some way. Accordingly, punctation might be sought fgr In Helisoma in 
which it Is as yet unknown. On the other hand, a near relationship between Bulininae 
and "Segmentlnlnae," both punctate, seems unlikely because of the known anatomical 
dissimilarities. 



^This investigation was supported (in part) by a research grant, E-2409, from the National 

Institute of Allergy and Infectious Diseases, U.S. Public Health Service. 
■^Present Address: Museum of Zoology, University of Michigan, Ann Arbor, Michigan, U.S.A. 

(115) 



116 H. J. WALTER 

A special affinity between the Bullninae and the punctate ?ancylid Burnupia is 
suggested by published anatomical data. The existence of punctation in the presum- 
ably primitive Ellobiidae, aside from pointing to their possible relationship to 
Planorbidae, might be taken as evidence that apical punctae represent a primitive 
character, although arguments to the contrary might be made. 

From the literature it is concluded that past investigation and description of 
shell microsculpture has been insufficiently exacting for adequate application to the 
complex biosystematics within basommatophoran groups such as Bulinus. 



J 



INTRODUCTION 

In a program of study of snail vectors 
of Schistosoma in the Republic of Liberia, 
West Africa, it was noted that a pattern 
of punctation was the dominant sculptural 
feature of the embryonic whorls of the 
shell of some available Bulininae. This 
finding led to a systematic examination of 
many Bulininae and limited numbers of 
other Basommatophora, from Liberia and 
elsewhere, to determine the presence or 
absence of apical punctation in these shells 
as well as to an inquiry into the litera- 
ture so as to find out what might be known 
generally about such sculpture in order to 
confirm or refute previous reports for the 
species I was able to investigate. 

The present paper, which is part of a 
broader investigation on the morphological 
basis of classificationin Basommatophoran 
groups, deals with the results of this in- 
vestigation of the punctate character in 
conjunction with the results from the lit- 
erature inquiry. 

MATERIALS 

In this study over 1600 shells were ex- 
amined for the punctate character of their 
nuclear whorl and of these the large ma- 
jority were of the species of African 
Bulininae that represent the 3 subgenera 
Bulinus s.S., Pyrgophysa Crosse, and 
Physopsis Krauss, of the genus Bulinus 
O. F. M311er,as they are recognized here*^ 
(Tables I and II). 



3The African Bulininae are now generally 
placed in the single genus Bulinus, with the 
former genus Physopsis occupying subgeneric 
rank, and the former genera Pyrgophysa and 
Bulinus combined in the subgenus Bulinus s.s. 
(see Mandahl- Barth, 1958). This grouping is 
based in part on anatomical data which are in- 
sufñcient in my opinion, and I Und it more con- 



No attempt was made to have the speci- 
mens oi Bulinus specifically identified by 
other authorities. Since this study is de- 
signed to test the prevailing and past tax- 
onomy, it is intended, in part, as a chal- 
lenge to the validity of the various species 
and forms that have been recognized. For 
the purposes of this paper it is only neces- 
sary to use an accepted system of classi- 
fication in order to demonstrate that many 
conchological forms from a wide geograph- 
ical area were included that represent a 
significant number of the probably valid 
species of the various species groups. For 
this purpose, it will be expedient to follow, 
in the main, Mandahl -Barth's (1958) sys- 
tem of classification and to cite the illus- 
trations of shells in it corresponding in 
form to those of the specimens studied 
(Table I). In following his system of 
classification for the identification of buli- 
nine species and " subspecies", attempts 
were made to apply given characters of 
the soft parts, as well as of shell sculp- 
ture, and sometimes of the radula, but, 
mainly because of inadequacy of the de- 
scriptive information, it proved necessary 
to rely almost entirely on the form of the 
shell in conjunction with geographical con- 
siderations. The decisions on the specific 
status thus made are for the most part 
uncertain, because rather few of the shells 
closely matched the illustrations. Also, 
some series of specimens from a given 
geographical area best match with figures 
of a variant that is supposed to be re- 
stricted to a widely distant area. Some 
specimens do not correspond to any of the 



venlent for the purposes of this paper to use 
the old group names as subgeneric designations, 
with Bulinus s.S. embracing the '4runcatus and 
tropicus groups," Pyrgophysa embracing the 
^^forskalii group," and Physopsis embracing 
the ^^africanus*' group of Mandahl- Barth. 



PUNCTATION OF EMBRYONIC SHELL IN BULININAE 



117 



descriptions in particular and some series 
of varying forms could as readily be as- 
signed to one "species" or "subspecies" 
as another. Even in assigning specimens 
to their subgenus, the given system could 
not be followed consistently. However, 
from my personal experience with conchol - 
ogy and soft anatomy, I was able to place 
all species in their respective "subgenera" 
with confidence. In one instance only some 
doubt existed about the subgeneric assign- 
ment of a series of "Pyrgophysa " ( the 
" cane s cens' ^ form in Table I), in consid- 
eration of certain microsculptural charac- 
ters (see p. 123). 

Although the number of valid forms 
treated here is debatable, most of the 
generally recognized African species of 
Bulininae assuredly were among those 
studied, and certainly included are a num- 
ber of other forms that some malacolo- 
gists would call good species. 



TABLE I. Bulinus s.l. studied 

Bulinus s.S. (25 localities) 

Sardinia Island, Italy 

1 locality: Field origin, Santa Teodora (lab- 
oratory-bred in London). The specimens cor- 
respond to B. truncatus truncatus (Audouln) 
form innesi Pallary: 53a. 4^ Contributed by 
P. L. LeRoux. 

Iraq 

1 locality: Baghdad. The series corresponds 
to B.t. truncatus (iorm innesi): 53a. Con- 
tributed by LeRoux. 

Egypt 
4 localities: Hallaba, Sanañr, and Qalyub, all 
in Qalyub Province and one laboratory-bred 
strain from "Egypt." Variants in the labora- 
tory strain closely approximate all of the fig- 
ures of B. t. truncatus', most of this labora- 
tory material and 2 of the field series, how- 
ever more closely resemble the innesi form: 
53a; the remaining lot is more like the form 
dybowskii Fisher (see Demian 1960, PI. I). 
Contributed by H. van der Schalle, except for 
the laboratory strain which was descended 
from a laboratory colony at the Tropenin- 
stitut, Hamburg, Germany and which was 
reared by the author in Liberia. 



4 The Fig. numbers cited here refer to the fig- 
ures in the plates in Mandahl- Barth (1958) 
unless specifically stated otherwise. 



Sudan 

2 localities: Khartoum and Khartoum area. 
One lot compares to B.t. truncatus of the 
innesi form: 53a. The other lot conforms to 
the "dybowskii^' form of B. truncatus. Con- 
tributed by LeRoux and van der Schalie, 

Tanganyika 

1 locality: Mwanzd, Variants resemble B. 
truncatus trigonus (Martens) and B. tropicus 
zanzibaricus (Clessin) and B. tropicus mu- 
tandaensis (Preston): 54a; 46 b, d; 47b. Con- 
tributed by LeRoux. 

Kenya 

1 locality: Kisumu, Lake Victoria. Partly 
grown in the laboratory, in London. These 
closely resemble B. t. truncatus of the innesi 
form: 53a. Contributed by LeRoux. . 

Northern Rhodesia 

9 localities: Mazabuka, Mbawa, and Lundazi 
areas. Some variants match with or tend 
toward B. truncatus trigonus and B. coulboisi 
(Bourguignat), while some resemble the East 
African B. sericinus (Jlckeli)^ of the trun- 
catus group; most other variants correspond 
with or tend to resemble the "subspecies" 
tropicus s.S. of B. tropicus Krauss, (includ- 
ing the "depressus" form of Haas), mu- 
tandaensis (Preston), allimudi (Dautzenberg) , 
and angolensis (Morelet): 54b; 57a,c; 50a,d; 
44a,d,h; 47a,c; 48a,d; and 45c,d. Some lots do 
not especially match any of the figured forms 
and other "subspecies" might be considered 
to exist among them. In form many of the 
Bulinus s.S. in some of these lots closely 
resemble Physopsis of the forms ugandae 
(Mandahl- Barth), globosus (Morelet) (includ- 
ing karongensis Smith), and africanus s.s. 
(Krauss): 41c, d; 42b,j; 38c, Not infrequently 
these samples actually included Physopsis 
species, but I could separate these out in all 
cases on conchological characters by very 
careful inspection. All lots contributed by 
LeRoux. 

Southern Rhodesia 

3 localities: Bulawayo and Salisbury areas. 
Most specimens are referred to B. tropicus 
tropicus; some resemble B. t. angolensis: 
44c,d,f; 45a. Contributed by LeRoux. 

Union of South Africa 

1 locality: Cape Province. The lot compares 
well with B. tropicus tropicus: 44c,d,f. Con- 
tributed by LeRoux. 

Ghana 

2 localities. Tamal a (laboratory-bred); "Gha- 
na". These specimens resemble B. trop- 
icus tropicus and B. truncatus rohlfsi (Cles- 
sin): 44g,h; 55a,b. Contributed by F. Wick- 
remasinghe. 

5 Mandahl- Barth considered B. sericinus to be a 
member of his '^tropicus group" (1958) but 
later (1960) transferred it to his "truncatus 
group". 



118 



H. J. WALTER 



Pyrgophysa (28 localities) 
Egypt 

1 locality: Qalyub Province. The specimens 
appear to be fairly typical B. /orsfeaí¿¿(Ehren- 
berg), but ribbing of the shell is not well- 
developed, and the sculpture is weak, muchas 
in: 59f. The larger shells {8-12mm long) tend 
toward: 59a, or j. Contributed by van der 
Schalle. 

Tanganyika 

2 localities: Mwanza area. The shells of both 
series are much like the Egyptian material of 
B.forskalii cited just above, and the above 
statements equally apply. Contributed by 
Le Roux and F. W. J. McClelland. 

Northern Rhodesia 

1 locality: Lochinwar, "in a cattle tank". 
The shells in this series are rather smooth 
and rather thickwalled and correspond to the 
"canescens Morelet" form of B. forskalii; 
they apparently are from the same original 
collection of LeRoux as those figured: 59k,l. 
Contributed by LeRoux. 

Southern Rhodesia 

1 locality: Bulawayo. Shells of this large 
series r<esemble the '^canescens Morelet" 
variant of B. forskalii in form: 59k, However, 
the shells are not smooth, but are strongly 
ribbed, with clearly developed "shoulder- 
keels" as in more typical B. forskalii, and 
they vary toward: 59c. Contributed by LeRoux. 

Union of South Africa 

1 locality: Cape Province. This large series 
particularly resemble B.forskalii as ñgured 
in: 59c. Contributed by LeRoux. 

?Unlon of South Africa 

1 locality: Kanlayis. Most of the specimens 
resemble the ^^ cane s cens*'* variant of B. 
forskalii in form: 59k, The shells however 
have well-developed ribbing instead of being 
smooth. Several small, short, and obese 
specimens among these must be taken to be 
B. reticulatus Mandahl- Barth: 58b,c. Con- 
tributed by LeRoux. 

Ghana 

1 locality. Ashanti region. The remarks made 
above for the series of B. forskalii from 
Egypt and Tanganyika also apply to this lot. 
Contributed by Wickremasinghe. 

Liberia 

20 localities: Eastern, Central and Western 
Provinces. Additional to these was abundant 
material from a laboratory colony started with 
specimens from one of the Central Province 
localities and reared through several genera- 
tions in Liberia. Most of the field and labora- 
tory shells correspond especially to B.for- 
skalii, and some variants seem more like B. 
scalaris: 59a,b,d,g; 60a,b. The few quite large 
specimens from the Ûeld (about 15 mm in 
length) closely resemble the figured shell 
types of B. forskalii: 59i,j. Collected (or 
reared) by the author. 



Physopsis (53 localities) 

Tanganyika 

2 localities: Mwanza area. Both collections 
consisted of undoubted B. nasutus (Martens): 
40b, с Contributed by LeRoux and McClelland. 

Northern Rhodesia 

9 localities: Lundazi, Lusaka, and Mazabuka 
areas. Many of the shell forms figured 
for B.globosus Morelet) and B. africanus 
(Krauss) are represented in these collections, 
but most tend to resemble B. globo sus: '^21. 
Contributed by LeRoux, 

Southern Rhodesia 

2 localities: Salisbury area. Much as for the 
Northern Rhodesian material cited just above, 
various shell forms of B. globosus and B. 
africanus appear to occur in these two lots; 
one large series especially conforms to B. 
africanus africanus: 38a, b. Contributed by 
LeRoux. 

Ghana 

1 locality: near Kumasi. The one young speci- 
men resembles B. globosus and it is especially 
strongly sculptured: 42a, Contributed by Wick- 
remasinghe. 

Liberia 
39 localities: At sites scattered widely over 
the Central and Western Provinces. Much ad- 
ditional material was obtained from a labora- 
tory-bred colony in Liberia that was started 
with specimens from one of the Central Prov- 
ince populations. The shells mostly conform 
to B. globosus especially, but some appear 
closer to B. africanus africanus: 42c,h; 38c. 
Some variants from the field especially could 
be taken for B. ugandae (Mandahl- Barth): 
41c. Collected (or reared) by the author. 



TABLE IL Material studied, other than 
Biilinus S.I. 

PLANORBIDAE 

Bulininae 
Indoplanorbus exustus (Deshayes): India, 1 
locality, UMMZ6 No. 80584; Ceylon, 1 lo- 
cality UMMZ No. 80582; and Afghan fron- 
tier, 1 locality UMMZ No. 80583. 

Planorbinae 

Planorbina ( =Biomphalaria) pfeifferi gaudi 
(Ranson)'^ : Liberia, W. Africa; several lo- 
calities in the Central Province, and 1 lab- 
oratory-bred colony descended from speci- 
mens from one of these localities. Collected 
and reared by the author. 



6 University of Michigan, Museum of Zoology 
catalog number. 

^There seems to be no doubt that, despite some 
controversy, Planorbina Haldeman 1843 is the 
oldest valid available name for the Planorbinae 



PUNCTATION OF EMBRYONIC SHELL IN BULININAE 



119 



Planorbina (=Australorbis) glabrata (Say): 1 
strain, field origin, Paramaribo, Surinam; 
reared by the author in the laboratory in 
Liberia; descended from an old stock at the 
Tropeninstitut, Hamburg, Germany. 
Gyraulus costulatus costulatus (Krauss): Li- 
beria, 1 locality in the Central Province, 
and a laboratory-bred strain descended 
from specimens therefrom. Collected and 
reared by the author. 
HelisomatinaeS 

Planorbarius comeus (Linné): England; 1 lo- 
cality, outskirts of London. Collected by the 
author. 

ANCYLTOAE 

Ferrissia (Walker) sp, or spp, : Liberia; 
several localities in Eastern, Central and 
Western Provinces. Collected by the author. 

LYMNAEIDAE 

Radix natalensis (Krauss): Liberia, llocality, 
Central Province, and a laboratory-bred 
strain descended from specimens there- 
from; collected and reared by the author. 
Sierra Leone, 1 locality; contributed by 
E. G. Berry. 
Pseudosuccinea sp: Union of South Africa, 1 
locality, Pokkraal. Contributed by Le Roux. 
" Stagnicola palustris group" : 1 strain, 
field origin, London, England, bred in the 
laboratory in London, Contributed by 
Le Roux. 

PHYSIDAE 

Physa sp: 1 lot, origin and collector uncer- 
tain; ?Liberia. 
Physa integra (Haldeman): U.S. A., 1 locality, 
Michigan, UMMZ No. 60492. 



METHODS 

The investigation of the occurrence of 
punctation in Bulininae and its relatives 
was divided into three phases. The first 
phase consisted of a concentrated study of 
many individuals from one colony each of 
the bulinine groups Bulinus s.S., Pyrgo- 
physa and Physopsis , kept on hand in lab- 
oratory aquaria at the Liberian Institute 
for Tropical Medicine in Liberia. The 
purpose of this part of the study was to 
determine how consistent the punctate 



acting as intermediate hosts of Schistosoma 
mansoni including the nominal genera Biom- 
phalaria Preston 1910 and AMsíraZor6¿s Pilsbry 
1934. 
8f. C. Baker, 1928. 



character was in its occurrence and rela- 
tive development among individuals of the 
colonies, and to work out appropriate 
techniques of observation, for which large 
amounts of expendable material were re- 
quired. Each laboratory strain provided 
abundant eggs from which large numbers 
of protoconchs were obtained and each also 
provided numerous shells of all growth 
stages up to adults. With these series it 
was possible to observe how erosion and 
encrustation of shells with algae and other 
environmental materials affected apical 
microsculpture as well as observation of 
the sculpture itself. Use of embryonic 
shells facilitated study of sculptural de- 
tails at high magnifications (see below) 
with a compound microscope, and allowed 
critical observations on the nature of 
punctae. 

The second phase of the investigation 
was concerned firstly with the examina- 
tion of much field material of Pyrgophysa 
and Physopsis, the two endemic bulinines 
of Liberia, that were collected at various 
places, and secondly with examination of 
material of many forms oiBidiniis s.l. 
from many other places in Africa and from 
some adjacent areas (see Table I). In 
this phase a "spot -check" procedure was 
followed: to reach conclusive decisions 
regarding the general presence or absence 
of punctation in the Liberian Bulininae, 
the series investigated were so chosen as 
to include specimens from the central and 
peripheral portions of their known ranges 
in the country, and also the more extreme 
conchological variants. In the available 
collections from areas outside of Liberia 
it was only in rare instances impossible 
to reach a decision for a particular series 
or variant, for reasons explained below. 
Some of the non-Liberian series were 
laboratory colonies reared elsewhere, and 
these contained shells of many juvenile, 
and sometimes embryonic, young; in these 
samples the presence of punctation was 
determined for many individuals. 

The third phase of the Investigation cov- 
ered at least several specimens of various 
species of non-bulinine Planorbidae, and 
at least a few shells of species of some 



120 



H. J. WALTER 



Other basommatophoran families. Only 
a few collections were available for this 
phase of the work, the main purpose of 
which was to determine if embryonic 
punctae might ever be fully lacking in any 
member of these groups. One breeding 
colony each of Planorbina (=Australorbis) 
glabrata {Say) ,Р1а}ЮГ bina (=Biomphalaria) 
pfeifferi gaudi (Ranson), G yrawZMS costu- 
latus (Krauss) and Radix (=Lymnaea) na- 
talensis (Krauss) were maintained at the 
laboratory in Liberia and provided shells 
of embryonic young for study. Part of 
this phase of the research was carried 
out in the Mollusk Division of the Museum 
of Zoology of the University of Michigan, 
in the United States. 

Early in this study it was found that 
shells could be cleaned by brushing, after 
they had been immersed for a few min- 
utes in full-strength commercial Clorox 
(sodium hypochlorite), a technique used 
routinely thereafter, for fresh or "alco- 
holic" specimens. Even when exposed for 
weeks, the shells are not altered physi- 
cally. This treatment completely removes 
the periostracum, external dirt and in - 
ternal traces of the body, without affecting 
the translucency of the shell. The thinner, 
smaller shells cleaned this way can be 
studied by transmitted light; in embryonic 
shells especially, the microsculptural de- 
tail can be seen with great clarity. Shells 
of progressively larger sizes are in gen- 
eral more thick-walled, especially in the 
region of the apical whorls, or of darker 
color, and will transmit less light, so that 
microsculptural details are seenwith diffi- 
culty or not at all clearly. Although most 
of the field material consisted of adult 
material, in all but a few series there 
were at least a few shells sufficiently 
small and thin to allow proper study by 
transmitted light; sometimes egg masses 
found preserved with the series yield- 
ed embryonic shells for study. In 
colorless shells, such as those of most 
Pyrgophysa, microsculpture was demon- 
strated more readily. Adult shells that 
could not be studied by transmitted light 
had to be viewed by less satisfactory re- 
flected light. In making the desired de- 



terminations, it was necessary to illum- 
inate the sculptural structures from many 
different angles, and often the exact angle 
of incidence of the light, arrived at by 
repeated trial and error, proved to be 
critical. In using this mode of illumina- 
tion the shininess and translucency of the 
surface of the shells cause interference 
with visual resolution of surface details, 
and even in the best material the presence 
or absence of punctation sometimes may 
be left somewhat in doubt even after in- 
tensive study at high magnification (see 
below). The method helped however, in 
determining the physical nature of micro- 
sculptural elements. Attempts were made 
to stain shells darkly in hopes of reduc- 
ing the surface translucency that inter- 
fered with observations, and aqueous solu- 
tions of basic fuchsin proved to be of 
some aid in this respect. Also, the spire 
on occasion was filled with black ink to 
provide a dark opaque background against 
which sculptural highlights might be more 
readily seen. 

It was found that shells, even from em- 
bryonic young, that had been cleaned with 
Clorox, readily turned white and opaque 
when only briefly exposed to a variety of 
agents in aqueous solutions, which include 
hydrogen peroxide in the ordinary weak 
concentration of commercial brands, a 
common detergent ("Tide") in low con- 
centrations , acids and potassium hydroxide 
in low concentrations, as well as sodium 
bicarbonate in high concentrations. Most 
or all of these agents cause a general 
surface erosion that rapidly erases the 
fine microsculpture. The very whitened 
shells, as would be expected, appear dark 
and featureless when placed between the 
observer and a strong source of light. 
Sometimes parts of shells that had been 
preserved with the animal proved to be 
whitened and opaque, apparently as a re- 
sult of chemical erosion of the internal 
surface of the whorls, and this on occa- 
sion was so pronounced as to prevent de- 
termination of microsculpturalcharacters 
in most specimens of a series. In some 
series the nuclear whorl itself was de- 
stroyed as a result of normal environ- 



PUNCTATION OF EMBRYONIC SHELL IN BULININAE 



121 




FIG. 1. Apex of shells of Bulinus s.l. showing punctation on the upper part of the embryonic 
whorl (highly enlarged). 

a) B. (Bulinus) truncatus (Audouin), Egyptian laboratory strain, adult specimen. 

b) B. (Pyrgophysa) forskalii (Ehrenberg), Li berian laboratory strain, adult specimen. 

c) B. {Physopsis) globosus (Morelet) , Liberian laboratory strain, young specimen. 



mental erosion but in practically all cases 
post-embryonic sculpture sufficed for a 
demonstration of punctation in a number 
of specimens of these series, when punctae 
were present. 

Microsculptural structures are much 
easier to demonstrate in shells having 
more scalariform (more "loosely coiled") 
apical whorls (e.g., "Pyrgophysa" forms). 
In more "tightly coiled" forms (such as 
most "Physopsis") the second whorl hides 
the larger part of the nuclear whorl and 
its sculpture, while in discoidal forms, 



especially in those having much expanded 
post-nuclear whorls, the embryonic shells 
may be hidden almost entirely. In cases 
like the latter, when it was desired to de- 
termine if punctae might be present on a 
small and very early fraction of the first 
whorl, it was necessary to break the post- 
nuclear whorls away to free the proto- 
conch for study. In such discoidal shells, 
the internal shell deposits on the first and 
second whorl are so laid down that they 
cover and obscure much of the nuclear 
whorl and its sculpture, and cannot be re- 



122 



H. J. WALTER 



moved; for this reason, embryonic speci- 
mens are of particular value in the study 
of the apical part of such shells, as was 
found in investigating the microsculpture 
oi Planorbina send Gyraidiis. 

When critically illuminated by trans- 
mitted light, nuclear punctation often can 
be seen fairly definitely at magnifications 
as low as 12. 5X, but then only in very 
clean material that is in excellent condi- 
tion. It is most often necessary to use 
magnifications of 32X, and over, as was 
done routinely in this study, for clear 
resolution of individual punctae when using 
transmitted light. In using reflected light, 
on the other hand, determination of the 
existence of punctae was often uncertain 
even at magnifications as high as 80X. 
Magnifications of 500X and even up to 
1250X (using an oil immersion objective) 
were used in checking sculptural micro- 
detail from time to time, sometimes while 
employing reflected light. Routinely the 
shells were kept immersed in fluid, usu- 
ally water, while being studied. 

RESULTS 

During the first phase of this study, in 
the examination of the hundreds of embry- 
onic shells oiBulinus (Bidimis) trimcahis 
of the Egyptian strain and of the Liberian 
strains of B. (Pyrgophysa) forskalii and 
B. (Physopsis) globosus that were bred in 
the laboratory, punctation was observed in 
all instances (see Fig. 1, a, b, c, but note 
that the shells illustrated have grown be- 
yond the proto conch stage to different 
sizes). The character proved to be con- 
spicuous in unmarred and clean embryonic 
specimens when observed with adequate 
magnification and when properly illumi- 
nated by transmitted light. 

It was found that, depending on slight 
differences in orientation of the specimen 
with respect to the source of light and 
with respect to one's eye, eachpuncta ap- 
pears as a brilliant microscopic spot of 
light, or as a dark minute ring enclosing 
a clear spot, or when foreshortened on 
curves, as a dark or bright short dash. 
Commonly, at lower magnifications, they 



seemed to be elevated ''nodular" struc- 
tures. However, close study of many 
specimens at magnifications of 500X and 
sometimes up to 12 50X and observations 
made at lower magnifications with re- 
flected light, showed that the punctae are 
well defined pits in the shell substance. 
These pits were seen to be arranged in 
an intersecting pattern of conspicuous 
spiral rows and more or less definite 
axial rows. Differences between the punc- 
tation of Bulinus s.S., Pyrgophysa and 
Physopsis were observed but basically the 
patterns were the same. There was no 
tendency for the punctal pattern to vary in 
degree of development, nor to tend toward 
obsolescence, although a consistent differ- 
ence in its relative prominence among the 
three subgroups of Bulinus was noted. In 
general it was easiest to discern puncta- 
tion in the Pyrgophysa and most difficult 
in the Bulinus truncatus, partly because 
of the differences in the size, thinness, 
color, and manner of coiling of the shells, 
but also on account of some difference be- 
tween the 3 groups in the relative coarse- 
ness of the punctae. For the very many 
laboratory- bred adult and undamaged B. 
(Pyrgophysa) forskalii that were studied, 
the nuclear punctation was always clearly 
demonstrated, even in shells which ex- 
ceeded 10 mm in length. In examinations 
of the many laboratory-bred ß, (В.) trun- 
catus and Я (Physopsis) globosus, alihowgh 
it was more difficult because of their 
darker, thicker, broader and more tightly 
coiled shells (especially the larger ones 
which often reached a length of 12 mm), 
nuclear punctation was always demon- 
strated in specimens that were relatively 
undamaged, when sufficient care and effort 
was used. Punctation was observed to 
continue onto the postembryonic whorls, 
but to an extent that differed among the 
strains representing the 3 different sub- 
genera. 

In the relatively few instances when 
punctae were unidentifiable in laboratory 
specimens, tell-tale whitening and opaque- 
ness of the shells indicated that they had 
been accidently exposed to an erosional 
agent; or else, in older individuals, com- 



PUNCTATION OF EMBRYONIC SHELL IN BULININAE 



123 



píete destruction of the nuclear whorl 
with its punctation had resulted from the 
more usual kind of erosional process that 
also occurs in field colonies. It was es- 
tablished beyond a doubt then, that nuclear 
punctation was a constant and always fully 
developed character in the three strains 
of laboratory-bred Btdinus s.S., P y rgo- 
physa and Physopsis. 

In observations of the Bulininae of 
strains of other geographical origin that 
were bred in other laboratories, and in 
examinations of field collections from Li- 
beria, and from other African countries, 
and from the Mediterranean and Middle 
Eastern areas, nuclear punctation was 
again identified in hundreds of specimens, 
except in a few particular instances, in 
which interfering factors, corresponding 
to those described above were clearly 
involved. However, even when the nuclear 
whorl was found to be lacking, the origi- 
nal presence of nuclear punctae was usu- 
ally inferable from the presence of post- 
embryonic punctation quite like that found 
in uninjured shells. Small shells, par- 
ticularly of hatching size, and embryonic 
ones obtained from occasional preserved 
egg masses, were in all cases seen to 
have the conspicuous basic punctal pattern. 
Again, forms of Pyrogophysa from the 
field, with the exception of one series, 
were found to have a somewhat more 
prominent and apparently coarser puncta- 
tion than the other Bulininae. The ex- 
ceptional series was that of the '^can- 
escens form oi B. (P.) for skalii" in which 
the punctae appeared relatively fine (and 
in which the development of post -nuclear 
punctation apparently was more like that 
which I have observed in Bulinus). Other- 
wise, various forms oí Bulinus s.s. in- 
cluding those of B. tropicus consistently 
appeared to have the least prominent and 
somewhat the finer punctation, as was 
found earlier in the laboratory -bred B. 
truncatus colony. 

In the study of Bulinus s.l., then, for 
practically all series that were obtained 
from the many places distributed over 
essentially the whole geographical range 
of the genus, nuclear punctae were dem- 



onstrated in at least one or in a few in- 
dividuals, and the punctate condition was 
definitely observed in over 1500 speci- 
mens (material from the laboratory col- 
onies included), that represented many 
species or forms, including members of 
Bulinus s.S., Pyrgophysa and Physopsis. 

As for the only remaining bulinine 
species, Indoplanorbis exustus, nuclear 
punctationwas definitely observed in some 
of the few shells from India and Ceylon 
that were studied. In these adult speci- 
mens the nuclear whorl was not in good 
condition and was quite thickened; this 
condition and the discoidal shape made 
the desired observations difficult, so that 
the punctal pattern could not be made out 
very clearly or be accurately compared 
with that found in Bulinus s.l. The punc- 
tae seemed to be relatively fine. 

Among the other Planorbidae studied, a 
conspicuous punctal pattern was observed 
on the nuclear whorl of the several speci- 
mens of Planorbarius corneus from Eng- 
land that were examined. In contrast, 
nuclear punctation was found to be totally 
lacking in all of some dozens of the ex- 
amined specimens of Planorbinai" Biom- 
omphalaria" and "Aiistralorbis") from 
Liberia and from Surinam and in the 
Gyraulus from Liberia. Of the non-plan- 
orbid snails that were studied, the embry- 
onic whorls of the Physa integra and 
Physa sp., the Ferris sia spp., and the 
several species of Lymnaeidae, were in 
all cases observed to be quite devoid of 
punctation. 

During this study the observations on 
punctae became involved to some extent 
with consideration of other microsculp- 
tural elements of the nuclear and post- 
nuclear whorls. Some of these elements 
might be referred to as nodules or as 
minute elevations and depressions, all of 
which occur in spiral series following the 
direction of the whorls and which are ar- 
ranged also in more or less definite trans- 
verse or axial series. These elements 
show a considerable range of diffère ntation 
in form,magnitude,complexityof arrange- 
ment, and visual prominence at the micro- 
scopic and macroscopic levels. Although 



124 



H. J. WALTER 



these structures tend to obscure punctae, 
particularly on certain parts of the whorls, 
and may in part tend to be confused with 
them, careful observations made at ade- 
quate magnifications have repeatedly shown 
that the punctae are a special type of 
structure that is well differentiated from 
other sculptural features of the shells of 
the snails that were investigated. It may 
be added that the relationship between the 
punctal pattern and the other sculptural 
structures gives the impression that the 
post -embryonic sculpture, in a sense, 
"evolves" from the punctae. 

LITERATURE ON NUCLEAR 
PUNCTATION 

This inquiry into the literature was in- 
tended to reveal specific information on 
punctation of the embryonic whorl par- 
ticularly in Bulininae. Secondarily, it was 
concerned with relating such information 
to any existing evidence of a taxonomically 
and phylogenetically significant pattern in 
the distribution of the character among 
other Planorbidae and among other Basom- 
matophora. It also became involved with 
some other aspects of microsculpture, as 
well as with certain other taxonomical- 
morphological matters, for reasons evident 
from the quotations cited below. 

As a means of bringing the results of 
this study on the occurrence of nuclear 
punctation into perspective in regard to its 
possible significance to current system- 
atics of the snails being considered here, 
extensive pertinent quotations, mostly from 
the more comprehensive works of leading 
authors follow. 

In reviewing Connolly's (1939) mono- 
graphic treatment of the freshwater fauna 
of South Africa for information on puncta- 
tion of the whorls of the embryonic shells 
of Bulininae, a series of informative state- 
ments were found. He says in regard to 
"Bulinus tropicus" (p. 501): " 1st fwhorl] 
smooth" and in regard to "Biilimis di- 
aphanus" (p. 505) (both Bulinus s.S.) 
''apical fwhorl] smooth". In reference to 
Bulinus [Pyrgophysa] forskalii" he says 
(p. 508): "extreme apex engraved with 



microscopic dots, arranged in spiral but 
not radial rows", and of the whorls of 
'^ Bulinus (Physopsis) africanus " he re- 
marks (p. 511): "1st minute, bearing ex- 
tremely faint, fine transverse microscopic 
wrinkles, 2nd with stronger transverse 
sculpture and microscopically engraved 
with punctate dots, arranged in regular 
radial and spiral lines, which usually dis- 
appear about the 3rd whorl. . . " In a ref- 
erence to "Bulinus (Physopsis) globo sus" 
(p. 512) Connolly gives no account of any- 
thing like "punctate dots, " but implies 
that this species is similar to B. (Phys- 
opsis) africanus in that respect. As for 
the many other Basommatophora that are 
treated in the same monograph, specific 
mention of punctation of the shell was 
found for one or more species of the 
genus Segmentina of the Planorbidae, of 
Burnupia of the Ancylidae, and oí Me lampus 
¡Lnd Phytia of the Ellobiidae. For none 
of these, except Burnupia is the puncta- 
tion stated to occur specifically on the 
first whorl or embryonic shell. 

Among 4 species of Segmentina that 
Connolly describes, only the one repre- 
senting the "subgenus" Hippeutis was 
stated (p. 496) to have punctation, which 
was said to be ' 'dense [ and] microscopic ' ', 
and which was said to be "probably of no 
[taxonomic] value". As for Burnupia, 
Connolly, following Walker (1923) and 
others, refers to "radially punctate" 
sculpture, usually if not always occurring 
on the "extreme apex" of the shell, as 
one of the diagnostic characters of this 
genus of many nominal species. He says 
in regard to 5 species of his section 
Melampus of the genus Melampus that 
the " early postapical whorls" are punc- 
tate, but no account is given of puncta- 
tion in descriptions of 2 other species. 
The apical whorl of one of these species 
of Melampus and the "extreme apex" of 
the one species of Р/г^/ш that is described 
are said to be "smooth" (p. 467, p. 462), 
and the same is stated or implied for 
related species that are considered by 
that author. In speaking of his section 
Melampus oi Melampus, he warns (p. 466) 
that punctae are only identifiable in a 



PUNCTATION OF EMBRYONIC SHELL IN BULININAE 



125 



shell that is "fresh enough to show it," 
and that they might erroneously be taken 
to be lacking in species described from 
shells that are not ' 'well -pre se rved". Fbr 
Pythia scarabaeusihinnê), another ellobiid 
H.Harry (1951) gives a clearly illustrated 
account of apical punctation also. 

In Pilsbry and Bequaert's monograph 
(1927) on freshwater mollusca of another 
large African region, "spiral lines of 
punctures" on the embryonic whorl were 
described (p. 129) as a character of 
Segmentina and of the "subgenus of Plan- 
orbis ", Hippeutis. The authors also ac- 
count for apical punctation in Burnupia. 
For the remainder of the many Basom- 
matophora (Planorbidae, Ancylidae, Lym- 
naeidae, Physidae, and EUobiidae) that 
are given attention in the monograph, no 
other mention of punctation was found. 
In an extended systematic account of many 
species and forms oí Bidinus s.l., the 
only statement found (p. 146) that might 
pertain to punctae is a reference to "spiral 
impressions" in " Physopsis africatm 
globosa ". 

Of the papers of Hubendick dealing with 
systematics within the Bulininae and Ba- 
sommatophora, two will be considered 
here, one that treats Bulinus s.l. (1948) 
and another the Planorbidae as a whole 
(1955). In the former paper, after discus- 
sing "Вг^гш^з senegalensis (Müller)", the 
type species of Bulinus, and '' Bulinus 
forskalii" as species having a particular 
type of elongate shell in common (p. 33, 
35), Hubendick describes the sculpture of 
that shell-type by saying (p. 43): " More- 
over, the shell shows a sculpture crossing 
the direction of the whorls." Also, in re- 
ference to the shell of Bulinus s.S., he 
states (1955, p. 523): " The nuclear whorls 
are usually providedwith striae" and: "In 
Physopsis\he columella is generally trun- 
cated. The nuclear whorls are usually not 
striated but have small dots spirally ar- 
ranged. Sometimes, however, the correla- 
tion between these characters does not 
hold good. All this means that Bulinus 
and Physopsis should be regarded as sub- 
genera of one genus {Bulinus) rather than 
as distinct genera." By inference, Huben- 



dick' s conclusion refers, in part, to ana- 
tomical considerations raised by him in 
the same paper. His account gives the im- 
plication that the nuclear whorls of Bulinus 
s.S., at least usually, have no "small dots", 
and it perhaps also implies that Physopsis 
may exceptionally have "striae" instead 
of dots. These quotations account for ail 
of the data on shell punctation found in 
these two papers. Shell characters are 
dealt with quite briefly in these and other 
works of that author that are known to 
me which deal primarily with interpreta- 
tions of the taxonomic significance of 
characters of the soft parts of the snails. 
Mandahl -Barth (1954), in reference to 
African Bulininae, says (p. 99): "The 
sculpture of the shell consists in most 
cases merely of delicate growth lines, but 
in some forms ribs or spiral sculpture 
may be present"; later (1958, p. 52) he 
states: "A spiral sculpture consisting of 
delicate lines or nodules may be present 
in some forms, especially on the upper 
half of the shell. '' The same author says 
oí "Bulinus (Pyrgophy sa) forskalii^' (1954, 
p. 110) that "The first whorl (the embry- 
onic shell) is smooth" and again later, of 
the whorls oí "Bulinus (Bulinus) forskalii" 
(1958, p. 85), that: "the first one is nor- 
mally smooth." He describes (1954, p. 
109) the first whorl of "Bulinus reticu- 
latus n. sp.", which he later assigns to 
his forskalii group (= Pyrgophysa) , as 
"smooth" and restates this (1958, p. 82) 
later. Mandahl -Barth further states (1958, 
p. 59) that "Physopsis has, as a rule, a 
distinct sculpture consisting of spirally 
arranged rows of small impressions — a 
type of sculpture never found in Bulinus 
s.S." and, also in the same paper (p. 60) , 
in reference to his "Africanus" group 
{=Physopsis): "In most forms a charac- 
teristic sculpture, consisting of spirally 
arranged rows of small transverse im- 
pressions or nodules, may be visible on 
the upper part of the shell at a magnifi- 
cation of about 25X. This sculpture has 
not been found in any of the forms belong- 
ing to the other groups." Here "other 
groups" refers to all African Bulininae 
except Physopsis species. Referring to 



126 



H. J. WALTER 



Bulinus (Phy sop sis) globo sus (1954, p. 113 
that author reports that "very delicate, 
small transverse lines, arranged in spiral 
series" occur on the ''upper whorls". 
"B. globo sus ugandae n.subsp.", he says 
(1954, p. 114), "completely lacks the spiral 
sculpture" that is found in typical B. 
globosus. For the same form (as species 
B. ugatidae) he later says (1958, p. 59 ) 
that it has "no particular sculpture at all" 
and, in the same work (p. 66), he reaf- 
firms this by saying that the species 
shows a "complete absence of spiral 
sculpture on the spire". In an addendum 
(1960) to his 1958 monograph there is one 
further pertinent statement referring to 
the newly recognized subspecies Bulinus 
(Physopsis) nasutus nasutus (p. 568): "The 
microsculpture consists of spirally ar- 
ranged rows of minute nodules or some- 
times punctures, as a rule more coarse 
on the upper whorls and becoming finer 
on the lower, but usually covering the en- 
tire shell. In other species of Physopsis 
the microsculpture is restricted to the 
spire." Mandahl-Barth (1954) also has 
described the apical punctation in the an- 
cylid Burnupia. 

C. A. Wright (1956) deals taxonomically 
with "6 species" of Bulininae from the 
Senegambia in northwest Africa. For 5 
of the 6 bulinine forms, he reports the 
existence of a "punctate pattern" or a 
"fine punctate pattern" on the "first 
whorl" or "nuclear whorl." The five re- 
portedly punctate species are "Bulinus 
guernei (Dautzenberg)" and "Bulinus seri- 
cinus (Jickeli),"both members oi Bulinus 
s.S.; "Bulinus ludovicianus (Mittre)" and 
"Bulinus forskalii (Ehrenberg), " both 
Pyrgophysa forms; a.nd "Bulinus jous - 
seaumei (Dautzenberg)" of the subgenus 
Physopsis. To my knowledge he is the 
first ever to account for punctate sculp- 
ture in Bulinus s.S. 

Although general sculptural features of 
the shell, including the presence of "nod- 
ules" in Physopsis, are described by 
Amberson and Schwarz (1953) in their 
account of African Bulininae, there is no 
definite reference to apical punctation. 
Nor does Demian (1960, pp. 10-12) in a 



lengthy treatment of shell characters in 
Bulinus tnmcatus of Egypt, give any indi- 
cation regarding nuclear punctation. 

In F. C. Baker's (1945) most detailed 
and comprehensive work on systematics 
in Planorbidae other than Bulininae, there 
is no mention of punctate sculpture in his 
account of the two "Bulinidae" he deals 
with, Isidora (=Physopsis) globosa and 
Indoplanorbis exustus. As for the 55 
genera and subgenera that he treats as 
Planorbidae, he gives a systematic ac- 
counting of the diagnostic conchological 
characters of each, and also devotes a 
special section to the shell characters of 
Planorbidae as a group. The only infor- 
mation referring to shell -punctation ap- 
plies to his subfamily Segmentininae, with 
definite specific reference to punctation 
of the embryonic whorls for each of 6 of 
the 10 recent (non-fossil) genera he placed 
in that category: Segmentina, Hippeutis, 
Polypylis, Pvigiella, Drepa^wtrema (Dre- 
panotrema s.s. and subgenus Fossul- 
orbis) and Platytaphius, and ?Helicorbis . 
He utilizes such terms as "spiral rows 
of small pits", "punctures", and "fine 
punctations" in the descriptions. He 
treats the punctate character as if it were 
one of the consistent features of each of 
these "genera" and, at one point (p. 107), 
he seems to imply that it might be diag- 
nostic for the "subfamily" but does not 
account for that character in the 4 other 
genera of Segmentininae. Since he gives 
relatively close attention to conchological 
matters in his taxonomic treatise, one 
would feel that his failure to mention 
shell -punctation for so many species and 
species groups means that the character 
is probably absent in most Planorbidae. 
Further reports on the occurrence of 
punctation in "Segmentininae" (in addition 
to Connolly's (1939) ioT Segmentina (Hip- 
peutis) ) have been recently given by Par- 
aense and Deslandes (1956a, b; 1958) for 3 
species of Drepanotrema. In dealing with 
a series of other mostly neotropical plan- 
orbids, including other "Drepanotrema" 
species, these authors have not otherwise 
reported the punctate character in their 
systematic and quite careful conchological 



PUNCTATION OF EMBRYONIC SHELL Ш BULININAE 



127 



descriptions. 

No records were found in the literature 
of the occurrence of punctation in Plan- 
orbina (Australorbis and Biomphalaria) . 

DISCUSSION AND CONCLUSIONS 

The preceding inquiry into the literature 
shows that punctation of the embryonic 
whorl or apex of the shell has been previ- 
ously reported by some authors for some 
species of each of the three subgenera 
constituting Bulinus sA. Punctation was 
recorded earliest and most frequently for 
Physopsis, but only very recently for 
Bulinus s.S. (where it is finest), its pres- 
ence in the former being sometimes con- 
sidered a diagnostic difference. For 
Pyrgophysa, in which I found the dots 
easiest to see, some records were also 
found. Taken on the whole, the literature 
considered seems to indicate that the pune - 
tation varies in degree of development, 
even to the point of obsolescence, among 
individuals of the species. The litera- 
ture would imply also that in Bulinus s.s. 
and in the Pyrgophysa group, the nuclear 
whorls usually lack punctation, and indeed 
may lack sculpture (may be "smooth") 
entirely. However, the results of my in- 
vestigation show that these reported ab- 
sences of punctation in Bulinus s.l. are 
in error. My findings show that puncta- 
tion of the embryonic whorls must be 
universal in Bulinus s.l. over its entire 
geographical range, and that it even oc- 
curs in the only other bulinine genus 
known, Indoplanorbis . Wright's findings 
on Bulinus of the Gambia, (a corner of 
Africa from which I had no material for 
examination), go along with my above con- 
clusion regarding 5mZ¿wms s.l. It has been 
shown here that nuclear punctation in the 
species of this genus is a character that 
almost certainly is always fully developed 
and that does not vary towards obsoles- 
cence. It was shown also, that in proper 
material of Bulinus s.l. (such as shells 
from very young or embryonic snails) and 
with proper equipment and techniques, 
nuclear punctae always can be observed 
clearly. It was also shown here that nu- 



clear punctation can be overlooked readily 
in shells unless they are relatively free 
of injury and unless very special care and 
special techniques in cleaning and examin- 
ing the specimens are applied. This cir- 
cumstance seems to account in large meas- 
ure for the lack of reports on punctation 
in so many cases. 

The literature inquiry has shown that, 
in general, characters of microsculpture 
in Bulinus s.l. have not been determined 
or applied in descriptive usage with suffi- 
cient exactitude. Above we have seen 
references to "striae, "to "small dots," to 
"small nodules"and to "spiral rows of 
small transverse impressions'* and the 
like, which give no more than "impres- 
sions" about the nature and magnitude of 
the sculptural elements. The ambiguity 
of such terms is shown by my findings 
that the spiral rows of small (transverse) 
impressions which are not truly pits, co- 
exist with spiral rows of punctae, which 
are well defined pits, and that spiral rows 
of small more or less nodular raised 
"lines" (also transverse), coexist with 
these. Authors, as quoted earlier in this 
paper, refer to shells of particular spe- 
cies of Bulinus as having small dots or 
striae and minute nodules "or sometimes" 
punctures, as if such characters were 
mutually exclusive. Statements to the 
effect that spirally arranged rows of small 
impressions are a type of sculpture never 
found in Bulinus s.S., that some species 
completely lack spiral sculpture, and that 
the microsculpture is restricted to the 
spire in species of the Physopsis group, 
are erroneous. Despite the fact that many 
bulinine shells seem to have smooth por- 
tions when viewed at low or no magnifica- 
tion and despite the fact that some forms 
(e.g. the "canescens " form of B. forskalii) 
may appear especially smooth, I have ob- 
served striation and spiral sculpture, at 
least at high magnifications, in all of the 
great many such examples in which I have 
sought for it carefully. Also, apparently 
гй! Bulinus s. 1. have the nuclear punctae 
arranged partly in radial as well as spi- 
ral rows, despite Connolly's (1939) con- 
trary statement regarding B. forskalii. 



128 



H. J. WALTER 



The relationship of these findings to 
the presently unsatisfactory state of tax- 
onomy in В ulinus s.l. is clear. The 
difficulties I encountered in trying to 
identify my bulinine material illustrates 
this situation. Although it may well be 
that the genetic relationships involved are 
so complex and of such a nature that a 
convenient and consistent classification of 
the forms may be impracticable, it is 
obvious that much thoroughly documented 
finely delineated morphological detail in- 
cluding that of the shell, which is not on 
hand at present, is a prerequisite for the 
making of a valid attempt at such a classi- 
fication. It should be supposed that exist- 
ing morphological differences between 
species of snails, as for other organisms, 
are in general of such slight magnitude 
that they need to be defined in explicit, 
refined terms. In this sense, and in re- 
gard to microsculpture, it can be said 
that the Bulininae are yet poorly known, 
despite the fact that a great many species 
and their varieties (or ^'subspecies") were 
originally diagnosed on shell characters 
alone and then were subsequently rede- 
scribed by later authors. It may be noted 
that my findings of nuclear punctation in 
Indoplanorbis brings conchological data, 
for the first time, in direct support of 
the data on characters of the soft parts 
on which that genus had been placed in 
the Bulininae. 

In respect to the occurrence of nuclear 
punctation in Planorbidae other than the 
Bulininae, the literature reveals that sev- 
eral workers have observed punctation 
(either on the nuclear whorl or in the 
region of that whorl) in various species 
referable to F. C. Baker's subfamily 
Segmentininae, and have failed to see 
punctae in other planorbids. Their nega- 
tive observations, together with my find- 
ings of a total lack of punctation in Plan- 
orbina and Gyraulus of the Planorbinae 
gives a strong implication that punctae 
are lacking in most planorbids. There 
are, however, reasons for assuming that 
conchological work has not been more 
thorough in respect to these snails than 
it has been for Bulininae, as shown above. 



and therefore one may expect that existing 
punctation has yet to be discovered in non- 
bulinine species that have been described. 
My finding of well -developed nuclear pune - 
tation in Planorbarius would support such 
a probability. 

Difficulties in demonstrating conchologi- 
cal minutiae, as was attempted in the 
usual ways and with the usual museum 
collections of small series of large and 
relatively opaque and often eroded and 
dirty shells, seem to have prevented stu- 
dents of Planorbidae from giving cogni- 
zance to the possible taxonomic - phylo- 
genetic significance of embryonic micro- 
sculpture. Among other gastropods, 
characters of the embryonic whorls have 
been reported as of value in the system- 
atics of the streptoneuran subclass Pro- 
sobranchiata (Iredale, 1911). In regard 
to the euthyneuran Basommatophora, api- 
cal microsculpture of the shell has been 
recognized as of importance in discern- 
ing taxa in the heterogeneous assem- 
blage of freshwater limpets, all formerly 
placed in the Ancylidae, which has al- 
ready been subdivided on various grounds 
(Walker 1923; Burch 1961, 1962), al- 
though further revision is needed. Re- 
garding the Planorbidae, as cited earlier 
in this paper, F. C. Baker (1945) has in- 
dicated that punctation of embryonic 
whorls may be characteristic for genera 
of his subfamily Segmentininae, while 
for the Ellobiidae, as also cited ear- 
lier, Connolly (1939) implies that " post- 
apical" punctation might be character- 
istic of the shells of all species of the 
''section Melampiis" of the genus Me- 
lampus . 

As for the possible relationships be- 
tween particular punctate taxa within Plan- 
orbidae, a good case might be made for 
a special affinity of Bulininae and the 
palearctic Planorbarius. A comparison 
of illustrations of the genital anatomy of 
Bulinus (Physopsis) and of Planorbarius 
in F. C. Baker's monograph (1945) re- 
veals obvious gross similarities, especi- 
ally in the female system, notwithstanding 
the evident differences in the penial com- 
plex (also see Demian, 1960, on Bulinus 



PUNCTATION OF EMBRYONIC SHELL IN BULININAE 



129 



truncatus Plate VI, figs. 22, 12)? Ob- 
servations in more detail of my own con- 
firm that the resemblance is even greater 
than might be inferred from these illus- 
trations. Such a relationship would per- 
haps have some bearing on the fact that 
a snail considered to be a Planorbarius 
(e.g. P. "dufoiirii " of the Iberian penin- 
sula) is the only non-bulinine species of 
planorbid that, like Bulinus, has been 
demonstrated to be a vector of Schisto- 
soma haematobium . A bulinine relation- 
ship might hold also for the near с tic 
Helisoma which seems to be closely al- 
lied to Planorbarius on anatomical and 
conchological grounds that F. C. Baker 
has advanced for including both of the 
genera in his subfamily Helisomatinae. 
There is reason in turn to suspect some 
particular relationship of the Heliso- 
matinae with the neotropical Taphius 
andecolus (d'Orbigny), on comparison of 
the illustrations of the genital anatomy of 
T. atidecolus in Paraense and Deslandes 
(1957) and Paraense (1958) with those of 
comparable organs (again excepting the 
penial complex) of Helisomatinae in Baker 
(1945). Also, reference to the illustra- 
tions of Bulinus anatomy in Demian(1960) 
should clarify this point. One may sup- 
pose therefore that Taphius might be 
punctate, and in fact this might be taken 
as demonstrated already, for according to 
Hubendick (1955) and Paraense(1958), Pla- 
tytaphius heteropleurus , a species which 
Baker (1945) describes as finely punctate 
on the embryonic whorl, is but a synonym 
of Taphius. These implied relationships 
would receive further support if embryonic 



9ln my opinion various workers have commonly 
overemphasized usage of characters of the 
terminal male genitalia (penial complex) in con- 
nection with systematics of Planorbidae and 
other Basommatophora, while disregarding the 
female genital structures; one may suppose 
that evolutionary changes in the latter are likely 
to be of a more fundamental, conservative na- 
ture, and that they therefore would provide the 
more weighty evidence in respect to broader 
relationships. Attention is drawn here to the 
major glandular developments of the "uterus" 
and "oviduct" of the female system, and to the 
prostate as well. 



punctation should be subsequently found in 
the American " helisomatines". 

A relationship of F . С. Baker's Segmen- 
tininae with Bulininae, on the basis of his 
anatomical data and on the data of Paraense 
and Deslandes (19 56a,b, among others) ap- 
pears unlikely. Planorbina (Australorbis 
and Biomphalaria) and Gyraiilus of the 
Planorbinae, on published anatomical 
grounds, which I can confirm from per- 
sonal observation, appear to be phylo- 
genetically distant from Bulininae (see es- 
pecially illustrations of the genital anatomy 
of ^'Taphius glabratus" and T. liebmanni " 
in Paraense (1958), oí "Planorbis " sopé- 
eles in Ranson (1953) -^^ and of Gyraulus 
in F. С Baker, 1945). On the limited 
current evidence given here these dis- 
coidal members of the Planorbinae are 
nonpunctate; this raises the question as 
to whether punctation is present or lack- 
ing in the "physoid" ("bulinoid") species 
of Planorbidae, placed by Hubendick (1955) 
under Planorbinae. Future investigation 
of this feature may provide evidence which 
could either weaken, or lend support to, 
that author's position in the matter. 

As for a possible genetic connection of 
Planorbidae (or divisions of the family 
that are characterized by punctation) with 
other particular Basommatophora, such a 
connection may be indicated in the case 
of the punctate ?ancylid Burnupia. Man- 
dahl-Barth's brief description (1954) of 
the prostate and penial complex of this 
freshwater African limpet would apply re - 
markably well to the known Bulinus spe- 
cies. The recent reports of an ancylid as 
a vector of a haematobium -like schisto- 
some in India (Gadgil and Shah, 1955) 
might be considered in relation to this 
type of data. If the primitive basom- 
matophoran EUobiidae, as their possession 
of apical punctation might suggest, are 
not especially related to apically punctate 
Planorbidae, then perhaps they provide 



10 This author places these 2 species of Plan- 
orbina, which have been previously assigned 
to Australorbis, in the synonomy of Taphius. 

11 Ranson by preference uses the old name 
Planorbis for the African species now usually 
placed under Biomphalaria. 



130 



H. J. WALTER 



evidence that punctation might be a prim- 
itive or even perhaps ancestral character 
in Basommatophora. The possession of 
the character in Planorbidae might then 
be taken as a mark of primitiveness of 
Bulinus and its relatives. It would how- 
ever, be possible to make a case for rel- 
ative primitiveness of the nonpunctate 
Planorbina on known anatomical grounds 
(in this connection see Hubendick, 1955, 
p. 533). One might relate this question 
to my demonstration in this investigation 
of a total lack of punctae in some Physi- 
dae and Lymnaeidae; at any rate the char- 
acter of nonpunctation should be pertinent 
toHubendick's(1947) argument that among 
the "higher limnic Basommatophora" (in- 
cluding Planorbidae and Ancylidae) the 
Lymnaeidae show primitive anatomical 
characters, and that the opposite case 
might hold for Physidae. The apical 
microsculpture of shells of Ancylidae has 
been given sufficiently close attention 
(Walker, 1923) so as to leave no ques- 
tion that most ancylids are nonpunctate, 
with which my limited data on Ferrissia 
agrees. Thus it appears that most Ba- 
sommatophora, including those of "higher 
limnic" categories, are nonpunctate. The 
negative evidence in the literature cited 
here might be taken as evidence that the 
Lymnaeidae are nonpunctate, in line with 
my findings. As a speculation on a prac- 
tical matter it may be considered that if 
the Physidae are indeed entirely devoid 
of punctation, and should it prove that 
the conchologically"physoid-bulinoid Plan- 
orbinae" of the Indo -Pacific region are 
punctate, a means would be provided for 
distinguishing between all conchological 
material of Planorbidae and Physidae that 
yet (see Hubendick, 1948, p. 60) may be 
catalogued arbitrarily as to family in 
museums. 

The questions about relationships 
among Basommatophora that are raised 
here may be understood when we have 
advanced further in the basic knowledge 
on which systematics depends. It maybe 
pointed out here that the so-called "more 
biological approaches" to systematics al- 



ways should be applied in connection with 
morphological data, and that a refined bio- 
systematics of Basommatophora will de- 
pend on further increases and refinements 
of our knowledge of, among other things, 
conchological morphology such as micro- 
sculpture. Previous classifications of the 
species of Bulinus and other Planorbidae, 
which have been treated with some urgency 
in recent years because of their impor- 
tance to medical and public health matters 
as vectors of Schistosoma blood nukes, 
have been attempted on insufficient data; 
a revision of the species is needed, in 
which microsculpture of the shell may 
prove to be of taxonomic importance. 

ACKNOWLEDGEMENTS 

By contributing most of the material of 
non-Liberian Bulininae that is described 
in this paper, the late Prof. P. L. LeRoux 
of the London School of Hygiene and Trop- 
ical Medicine, London, England, made this 
investigation possible ; with warmth I recall 
the courtesy, enthusiasm, and spirit of co- 
operation which he showed in helping me 
choose samples from the very large and 
valuable material of African Bulininae that 
he had amassed through conscientious and 
sustained effort in the field and labora- 
tory. For contributions of further speci- 
mens my thanks go to Dr. Elmer Berry 
of the Natural Institutes of Health, Wash- 
ington, D.C., U.S.A. ; to Mr. W. F. J. Mc- 
Clelland of the East African Medical Sur- 
vey at Mwanza, Tanganyika; to Dr. F. 
Wickremasinghe of the Kintampo Medical 
Field Unit in Ghana; and to Prof. Henry 
van der Schalle of the Museum of Zoology, 
University of Michigan, U.S.A. Prof, van 
der Schalle deserves further grateful ack- 
knowledgement for his support and aid, 
which included making arrangements for 
my use of the excellent facilities for mol- 
luscan study at the University of Michigan. 
For aid in collecting in the field and in 
rearing of snails in the laboratory in 
Liberia, I wish to thank Dr. D. M. Levine 
of the Liberian Institute for Tropical 
Medicine, and my thanks also go to my 



PUNCTATION OF EMBRYONIC SHELL IN BULININAE 



131 



Liberian assistant of that Institute, Mr. 
S. Vonleh and Mr. J. Gibson, for similar 
aid. 

I am indebted to Mrs. Anne Gismann 
and to Dr. J. B. Burch, of the Museum 
of Zoology, University of Michigan, for 
much aid given with sustained interest, 
in the preparation of this publication. 

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, 1939b, Remarques sur l'appareil 



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génital de l'Indoplanorbis exustus; affinités 

de cette espèce avec les Bulinidés. Bull. 

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mollusks of Uganda and adjacent territories. 

Ann. Kon. Mus. Belg.-Congo, Tervuren,in8° 

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soma. African Biomphalaria and Bulinus. 

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"Platytaphius**, and "Taphius** (Pulmonata, 

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BrasiL BioL, 16(4):491-499, 
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'^^rëpânotrema*' . II, "D. melleum" (Lutz, 

1918). Rev, Brasil BioL, 16(4):527-534. 
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275-281. 

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aquatic mollusks of the Belgian Congo, with 
a geographical and ecological account of 
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bidae Africains. BulL Soc. Path. éxot.,46(5): 
783-810. 

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sur trois planorbes Africains: Planorbis 
pfeifferi Krauss, Planorbis adowensis Bour- 
guignat, Planorbis ruppellii Dunker. Bull. 
Mus. 2e ser., 24(2):206-212. 

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Indoplanorbis exustus (Mollusca Pulmonata). 
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Africa. 82 p. London, 

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species of the molluscan genus Bulinus 
(Planorbidae) from Senegambia, Proc. Malac, 
Soc, London, 32(3):88-104. 



132 H. J. WALTER 

ZUSAMMENFASSUNG 

PUNKTIERUNG DER EMBRYONALEN SCHALE IN DEN 

BULININAE (PLANORBIDAE) UND EINIGEN ANDEREN 

BASOMMATOPHOREN UND DEREN MÖGLICHE 

TAXONOMISCH-PHYLOGENE TISCHE 

BEDEUTUNG. 

Das Vorkommen einer mikroskopischen Punktierung des embryonalen Gehäuse- 
umganges wird hier zum ersten Male als beständiges Charakteristikum der Gattung 
Bulinus s.l. in ihrer gesamten geographischen Ausbreitung angegeben, sowie auch 
für Indoplanorbis , die einzige andere zu den Bulininae gehörige Gattung, gemeldet. 

Es wurden die Gehäuse von über IbQQ Bulinus s.l. aus 106 verschiedenen Labo- 
ratoriums- order Freilandskolonien untersucht, insbesondere solche liberischer 
Herkunft, aber auch viele aus über die Länge Afrikas verstreuten Fundorten, sowie 
einige aus Sardinien und Irak. Das Untersuchungsmaterial umfasste zumindest 14 
verschiedene Arten, Unterarten oder Varietäten der Untergattungen BmZî'wms s.S., 
Pyrgophysa und Physopsis. Punktierung konnte durchwegs nachgewiesen werden, 
ausser in seltenen Fällen wo der Nachweis durch Beschädigung der Schale oder son- 
stige imgünstige Umstände verhindert wurde. Die^^punctae" sind scharf umrissene 
Grübchen die ständig in ganz bestimmter, für jede der 3 subgenerischen Gruppen 
etwas verschiedener Anordnung auftreten. Die grundlegenden Beobachtungen über die 
Natur und Anordnung dieser punctae sowieüber andere Elemente der Feinstskulptur 
wurden an zahlreichen embryonalen Gehäusen aus Laboratoriums kolonien gemacht, 
wobei auch die Beständigkeit der Pimktierung in allen 3 subgenerischen Gruppen 
festgestellt wurde. 

Apikale Punktierung des Gehäuses ist zwar schon im Schrifttum für jede dieser 
Untergattungen angeführt worden, jedoch nur für sehr wenige Arten und im all- 
gemeinen in so wenig aufschlussreicher Weise dass man sogar bei diesen auf ihre 
Abwesenheit in einigen Individuen oder Populationen schliessen könnte. Auch ge- 
stattet die gewöhnlich wenig genaue Ausdrucksweise, wie z.B. Beschreibungen von 
"Tupf Chen", "Knötchen", "Perforierungen" oder " Einprägimgen" , vereint mit den 
nur spärlichen Angaben früherer konchologischer Beschreibungen, den Schluss, dass 
in Bezug auf Feinskulptur des Gehäuses, die Bulininae noch ungenügend bekannt sind, 
was auch für die Basommatophoren im allgemeinen zutrifft. Zweifelsohne wurde 
diese Punktierung deshalb so oft übersehen weil sie nur in verhältnismässig un- 
beschädigten, sehr gut gereinigten Schalen bei angemessener Vergrösserung und 
kritischer Beleuchtung erkennbar ist. Ihr erfolgreicher Nachweis beruht haupt- 
sächlich auf des Verfassers Verfahren die Gehäuse mit unterchlorigsaurem Natrium 
zu reinigen, wodurch Beobachtung der Einzelheiten des skulpturellen Reliefs bei 
durchfallendem Licht ermöglicht wurde. 

Unter den nicht bulininen Planorbiden ist embryonale Punktierung bei der 
Segmentina Gruppe und bei Platytaphius (? Taphius) bekannt und, innerhalb der an- 
deren Basommatophoren, bei der "ancyliden" afrikanischen Napfschnecke Bumupia 
und bei den Ellobiiden Melampus, Phytic, und Pythia. Eigenen Untersuchungen an 
einigen Arten nicht bulininer Planorbiden zunach, war sie ebenfalls in Planorbarius 
corneus vorhanden, fehlte jedoch völlig in Planorbina (Australorbis und Biompha- 
laria) und in einer untersuchten Gyraulus Art. Ihr Nichtvorhandensein wurde eben- 
falls in verschiedenen Lymnaeiden, in Physa und Ferrissia festgestellt. 

Bei den Basommatophoren wurde bisher apikale Mlkroskulptur nur in der Fa- 
milie Ancylidae als taxonomisch wertvolles Kriterium erkannt. Ihrer möglichen 
taxonomisch-phylogenetlschen Bedeutung Inder Bestimmung von den innerhalb dieser 
Unterordnung zwischen verschiedenen Rangstufen herrschenden Beziehungen wurde 
hingegen nur sehr wenig Aufmerksamkeit geschenkt. 

Hier werden nun einige Fragen über die möglichen phylogenetischen Zusam- 
menhänge in Bezug auf Punktierung innerhalb der Unterordnung aufgeworfen. Was 
Beziehungen zwischen einzelnen Planorbidengruppen zueinander anbelangt, so wird 
darauf hingewiesen, dass den Folgerungen des Autors nach, auf grund einiger anato- 
mischer Merkmale, ein gewisses Verwandtschaftsverhältnis zwischen den Bulininae, 
dem paläarktischenPZanorbarzMS, dem nearktischen HeZî'sowa und dem neotropischen 
Taphius andecolus zu bestehen scheint. Es wäre daher Punktierung noch in 



PUNCTATION OF EMBRYONIC SHELL IN BULININAE 133 

Helisoma, der einzigen dieser Arten bei der sie unbekannt ist, zu suchen. Dagegen 
erscheint eine engere Beziehung Zwischen den Bulininae und " Segmentininae" , 
welche beide punktiert sind, auf grund bekannter anatomischer Unterschiede un- 
wahrscheinlich. 

Ferner wird ein näherer Verwandtschaftsgrad zwischen den Bulininae und der 
punktierten ?ancyliden Burnupia durch veröffentlichte anatomische Befunde na- 
hegelegt. Schliesslich könnte das Vorhandensein einer Punktierung in den mut- 
masslich primitiven EUobiiden - abgesehen davon, dass sie auf eine mögliche Ver- 
wandtschaft mit den Planorbiden hinweist- auch vielleicht als Beleg dafür angesehen 
werden, dass apikale Punktierung einursprüngliches Merkmal darstellt, obwohl auch 
eine gegenteilige Beweisführung geltend gemacht werden könnte. 

Durchsicht des Schrifttums führt zu dem Schlüsse, dass die bisherigen die 
Feinskulptur der Schale betreffenden Untersuchungen und Beschreibungen nicht 
genügend genau sind um hinreichende Rückschlüsseauf die verwickelte Biosystema- 
tik innerhalb solcher Basommatophorengruppen, wie z.B. Bulinus sie darstellt, zu 
gestatten. 



RESUME 

PONCTATION DE LA COQUILLE EMBRYONNAIRE DANS 

LES BULININAE (PLANORBIDAE) ET QUELQUES AUTRES 

BASOMMATOPHORES AINSI QUE SA SIGNIFICATION 

TAXONOMIQUE ET PHY LOGE NE TIQUE POSSIBLE 

Une ponctation microscopique de la coquille embryonnaire est ici décrite pour 
la première fois comme caractère constant du genre Bulinus s.l. dans toute sa dis- 
tribution géographique et se trouvant aussi dans V Indoplanorbis , le seul autre genre 
reconnu dans les bulininés. 

L'auteur étudia plus de 1500 coquilles de Bulinus s.l. appartenant à au moins 14 
espèces, sous-espèces ou variétés des sous-genres Bulinus s.S., Pyrgophysa et 
Physopsis et provenant de 106 différentes populations soit de laboratoire soit 
d'ambiance naturelle, originaires tout particulièrement de la liberie, mais aussi 
de nombreuses autres localités africaines disséminées sur la longueur du continent 
africain, ainsi que de la Sardelgne et de l'Iraq. La présence d'une ponctation fut 
observée dans tous les spécimens étudiés, excepté quand ils étaient endommagés ou 
quand certains autres circonstances en entravaient la détermination. Nous entendons 
par "ponctation" un système de "/)M«ctee" ou fossettes très bien définies, arrangées 
en un dessin constant dominant la microsculpture , et ne différant que de peu dans 
chacun des 3 sous-genres de Bulinus. L étude d'un grand nombre de bulinins em- 
bryonnaires cultivés au laboratoire fournit l'information fondamentale au sujet de 
la nature et l'arrangement de cette ponctation, ainsi que des éléments autres de la 
microsculpture et en démontra la constance dans les 3 groupes sub-génériques. La 
présence d'une ponctation apicale de la coquille a déjà été relevé au préalable dans 
la littérature pour chacun de ces sous-genres, mais elle ne se trouve indiquée que 
pour un nombre très restreint d'espèces et ce de manière à faire croire qu'elle 
pourrait manquer même dans celles-ci en certains individus ou populations. D'autre 
part Tusage d'habitude peu exact de termes descriptifs tels que "points", "nodules", 
"ponctures" ou "empreintes", joint aux bien maigres indications se trouvant dans 
les descriptions conchyliologiques antérieures, démontre, qu'en ce qui concerne la 
microsculpture, les espèces bulininés sont encore peu connues, ce qui d'ailleurs 
s'applique également aux basommatophores en général. Le fait que si fréquemment 
cette ponctation n'a pas été remarquée est certainement dû à ce qu'elle n'est visible 
que dans des spécimens relativement peu endommagés, très propres, examinés à la 
juste magnlflcatlon et illuminés critiquement. Le succès obtenu à la démontrer dé- 
pend largement de la tecnique ici employée à nettoyer les coquilles à Г hypochlorite 
de soude, ce qui permet l'étude des détails du relief sculpturel en transparence. 

Parmi les planorbidés non-bulinins, la ponctation embryonnaire était déjà 
connue dans legroupede "5е^теи^ил" etdans le Platytaphius (7=Taphius) et, parmi 
les autres basommatophores, dans l'"ancylide" africain Bumupia et les ellobiides 
Melampus, Phytia et Pythia. Ici, d'après examen de quelques espèces planorbidés 
non- bulininés, la présence d'une ponctation nucléaire de la coquille est rapportée 



134 H. J. WALTER 

pour le Planorbarius comeus, ainsi que son absence totale en Planorbina {Austra- 
lorbis et Biomphalaria ) et dans une espèce de Gyraulus. Elle était également 
absente dans un nombre d'espèces lymnéides, dans Physa et Ferrissia. 

Parmi les basommatophores, la microsculpture apicale a été reconnue avoir 
und valeur taxonomique au sein des ancylides; mais, pour le reste, son importance 
taxonomique et phylogénétique n'a reçu que l'attention la plus restreinte. Quelques 
questions se posentmaintenant au sujet des connections phylogénétique s possibles en 
rapport à la ponctation. En ce qui regarde les groupements à l'intérieur des plan- 
orbidés, il existe, à l'avis de l'auteur, en vue de caractères connus, une certaine 
parenté entre les bulinlnés, le Planorbarius palear etique, le Helisoma néartique 
et le Taphius andecolus néotropical. En conséquence , la présence d'une ponctation 
serait à rechercher епЯе/гзоша, le seul de ces genres d'où on l'ignore. Par contre, 
un proche rapport entre les Bulininae etles "Segmentininae," tous les deux pourvus 
de ponctation, semble improbable en vue de leurs différences anatomiques connues. 
En ce qui concerne les relations entre bulininés et groupes basommatophores non- 
planorbidés, une affinité particulière avec l'{?) ancylide Burnupia est suggérée par 
les données anatomiques publiées. 

Quant au caractère même de ponctation, sa présence dans les ellobidés sup- 
posément primitifs - apart Г indice qu'elle pourrait fournir pour une relation 
possible avec les planorbidés - pourrait être interprêtée comme indice de sa pri- 
mitivité, quoiqu'une argumentation contraire soit possible. 

Finalement nous concluons de Г étude de la littérature que ni l'examen ni la 
description de la microsculpture du test n' ont encore été exécuté assez rigour- 
eusement pour être appliqués adéquatement à la biosystématique complexe prévalant 
parmi les groupes basommatophores tels que Bulinus. 



RESEÑA 

LA PUNTUACIÓN DE LA CONCHILLA EMBRIONAL EN BULININAE 
(PLANORBIDAE) Y ALGUNOS OTROS BASOMMATOPHORA Y SUS 
POSIBLES IMPLICACIONES TOXONOMICAS Y FILOGENETICAS 

La puntuación microscópica de la conchilla embrional es indicada por primera 
vez como una característica constante de Bulinus s.l. sobre su área geográfica, y 
también existiendo en el solo otro género reconocido del Bulininae, Indoplanorbis . 

El autor estudió más de 1,500 individuos conchxWdiS áe Bulinus s.l, de por lo 
nienos 14 especies, subespecies, o variedades de los subgéneros Bulinus s.S., 
Pyrgophysa y Physopsis, representando 107 poblaciones diferentes de laboratorio y 
en sus habitats naturales, particularmente de Liberia, así también de Sardinia e 
Iraq y de otras localidades numerosas a través de Africa. La puntuación fué 
observada en cada una de las especies menos en aquellas en que las conchillas 
estaban destrisuidas o anuladas por otros factores. Los puntos "punctae'' son hoyos 
bien difinidos que ocurren en una estructura básica que domina la microéscultura 
embrionaria, modificados ligeramente en los 3 grupos. El estudio de un gran número 
de conchillas embrionarias, de poblaciones criadas en laboratorio dio información 
básica sobre la naturaleza y distribución de los puntos y de otros elementos y 
confirma la constancia de puntuación en cada uno de los 3 grupos subgenéricos 
de Bulinus. La puntuación apical de las conchillas de cada uno de estos subgéneros 
se ha reportado por otros investigadores, pero solamente para algunas especies, 
la literatura previa sugiere que hasta en estas especies algunos de los individuos 
o poblaciones dejan de desarrollar esta característica. El uso commun pero in- 
exacto de los términos como "manchas, módulos" y datos insuficientes en previas 
descripciones, demuestran que las especies de Bulininae, así como todos los Basom- 
matophora en general son muy mal conocidas con respecto a la microéscultura. La 
puntuación debió de haberse pasado por trascurrido porque se puede indentificar 
solamente en conchillas que estén limpias e intactas con aumento e ílluminación 
apropiados. El éxito en demostrar la puntuación dependió mayormente en la técnica 
usada por el autor al limpiar las conchillas con hipoclórito de sodio, el cual per- 
mitió el estudio del detalle escultural por medio de luz transmitida. 



PUNCTATION OF EMBRYONIC SHELL IN BULININAE 135 

Entre Planorbidae no-bulininae la puntuación embrional se sabía había ocurrido 
en el "grupo Segmentina" y en Platytaphius {?=Taphius), y entre otros Basom- 
matophora en el "ancylid" Bumupia de Africa; y en los ellobidos Melampus, 
Phytia, y Pythia. Examinando varias especies de planorbidos no-bulininae el autor 
reporta la existencia de puntuación nuclear en Planorbarius corneus, y totalmente 
ausencia en Planorbina {Australorbis y Biomphalaria) y enlas especies de Gyraulus. 
La misma ausencia de la puntuación se notó en varios Lymnaeidae, en Physa y en 
Ferrissia. 

Entre los Basommatophora, la microéscultura apical ha sido aceptada con valor 
taxonómico entre los Ancylidae, pero de otro modo, su posible significación 
taxonómica-filogenética en relación con otros niveles de taxonomía entre el sub- 
orden, se le ha dado hasta ahora muy poca atención. El autor, aquí, da lugar a 
prequntas sobre laposibilidadfilogenética entre el suborden en relación-grupal entre 
los Planorbidae, se considera que los Bulininae, los paleárticos Planorbarius , los 
neártlcos Helisoma y los neotrópicos Taphius an<¿ecoZMS parecen estar relacionados 
de alguna manera. Por consiquiente, la puntuación en Helisoma se pudiera explorar, 
ya que tadavía no ha sido observada en ella. Una relación cercana entre Bulininae 
y " Segmentininae", ambas puntuadas, parece improbable por lasdesimejanzas ana- 
tómicas conacidas. 

Una afinidad especial entre los Bulininae y la punteada ?ancylid Bumupia se 
sugiere por medios de datos anatómicos y publicados. La existencia de puntuación 
en el Ellobiidae, a parte de indicar su relación posible con los Planorbidae, se 
puede tomar como evidencia que las puntuaciones apicales representan un carácter 
primitivo, aunque se pudiera discutir lo contrario. 

De la literatura se concluye que las investigaciones y descripciones pasadas de 
la microéscultura han sido insuficientemente exactas para hacer aplicaciones ade- 
cuadas en algo tan complejo como la biosystemática dentro de los grupos Basom- 
matophora tan como Bulinus, 



КОНСПЕКТ 

ПУНКТИРОВКА ЭМБРИОНАЛЬНОЙ РАКОВИНЫ BULININAE (PLANORBIDAE) 
И НЕКОТОРЫХ ДРУГИХ БАС0МГ^1АТ0Ф0РНЫХ МОЛЛЮСКОВ И ЕЕ ВОЗМОЖНОЕ 
ЗНАЧЕНИЕ В СИСТЕМАТИКЕ И ФИЛОГЕНИИ 

Гарольд Я. Волтэр 

Впервые сообщается о пунктировке эмбиональной раковины 
как общий характер рода Bulinus s.l. в его географическом 
распространении, которая также встречается только в роде 
Indoplanorbis подсемейства Bulininae , 

Автор исследовал более 1 ,500 экземпляров раковины этого 
рода, по крайней мере 14 видов, "подвидов" или его вариантов, 
относящихся к подродам Bulinus s.S., Pyrgophysa и Physopsis; 
они были представлены 106 различными природными и лаборатор- 
ными колониями, особенно из Либерии, но также и из Сардинии, 
Ирака и из многих других местностей через всю длину Африки. 
Пунктировка была наблюдаема в каждом неповрежденном экземпля- 
ре. Пунктировка состоит из ясно-выраженных ямочек, как посто- 
янное характерное отличие микроскульптуры, которая несколько 
разнится в трех подродах. Обследование больших количеств 



136 H. J. WALTER 

раковин, выращенных в эмбриональной лаборатории, дало основ- 
ные сведения о характере и расположении точек (pmictae) и 
других микро-скульптурных элементов и показало постоянство 
определенной пунктировки для трех подродовых групп рода Були- 
нус. Пунктировка эбрионального оборота раковины была упомя- 
нута други>а1 авторами, для каждого из этих подродов, но толь- 
ко для очень немногих видов и прежние работы указывали на 
непостоянство этой характеристики. Обыкновенно неточное упот- 
ребление таких терминов как "точки" ,"уолщения" , "узелки", 
"пунктир" или"оттиск", совместно с недостаточными данными в 
описаниях конхиологической литературы прошлого, показали 
недостаточное знание микроскульптуры подсемейства Булининэ, 
То же можно сказать и всей группе Басомматофора вообще. 
Пунктировка в прошлом не была замечена во многих случаях, 
ибо она ясно выражена только в хорошо сохранившихся неповреж- 
денных раковинах, при условии необходимых увеличивания и осве- 
щения. Успех демонстрации пунктировки зависел главным образом 
в очищении завитка раковины раствором Na cl О , который 
позволяет изучать детали его микроскульптуры. 

Между видами семейства Planorbidae, помимо подсемейства 
Вга11п1пав эмбриональная пунктировка была замечена в "группе 
Сэгмэнтина", в Platytaphius ( ? Taphius), и в других видах 
Басомматофора, в "анкилозных" Витирга в Африке и в эллоби- 
идах Melampus, Phytia Pythia. После исследования нес- 

кольких видов планорбидов, кроме подсемейства Булиминэ, автор 
докладывает о наличии эмбриональной пунктировки в раковине 
Planorbarius corneus и полное отсутствие ее у Planorbina 
(Australorbis и Biomphalaria) и у видов Gyrauliis, 

То же отсутствие пунктировки было найдено у различных Lyra- 
naeldae,y Physa и у Ferrissia. 

Между видами Бсомматофора, микроскульптура завитка была 
принята, как фактор классификации в семействе Ancylidae, 
но в другом отношении она может иметь значение в системати- 
ке на всех уровнях подотряда, что до сих пор получило мало 
внимания. Авторвыдвигает некоторые вопросы о филогенетичес- 
ких возможностях внутри подотряда в связи с пунктировкой. 
Что же касается взаимного родства групп в семействе Planor- 
bidae, считается возможным, что на основе характера анато- 
мии подсемейства Булининэ, палеоарктический род Планорбари- 
ус, неарктический - Хелисома и неотропический вид Taphius 
andecolus все находятся в родстве. 



PUNCTATION OF EMBRYONIC SHELL IN BULININAE 137 

С другой стороны близкое родство между Bulinlnae 
Segmentininae ^ qQq грушш с пунктировкой завитка, 
кажется мало вероятным по причине анатомического несходства. 

Опубликованные анатомические данные указывают на особен- 
ное родство между Bulininae и ? анкилозным Витирга. Нали- 
чие пунктировки в считающихся примитивными Эллобиидах, понн- 
мо из возможного родства с сем. Планорбидэ, может быть при- 
нятым за доказательство, что пунктировка эмбрионального обо- 
рота может служить признаком примитивного характера, что, 
конечно, может быть оспариваемо. 

Из литературы сделано заключение, что прошлое изучение 
и описание микро скульптуры завитка раковины были недостаточ- 
но полны для применения их в сложных вопросах систематики 
в границах групп Басомматофора, как например, род Bulinus. 



МА1АСОЮС1А, 1962, 1(1): 139-161 

DISTRIBUTION OF SPHAERHDAE (PELECYPODA) IN MICHIGAN, U.S.A. "^ 

William H. Heard 2 
Museum of Zoology, Ann Arbor, Michigan, U.S.A. 

ABSTRACT 

About half of the 31 species (and forms) of sphaeriid clams now inhabiting 
Michigan are of a more or less general distribution in the state, while the re- 
mainder have a geomorphologically or ecologically restricted range. During the 
Pleistocene Epoch those sphaeriids present in the basin of the Mississippi River 
presumably colonized the Michigan region from the south, as did the unionid 
mussels, by upstream migration through the post-glacial streams that drained the 
enormous water bodies occupying the region of the present Great Lakes, The 
major routes of migration from the Mississippi drainage were: (1) into Michigan's 
Upper Peninsula, the Fox River Valley in eastern Wisconsin and (2) into the Lower 
Peninsula, the niinois-Des Plaines channel, which drained glacial Lake Chicago (the 
southern basin of the present Lake Michigan) and the glacial Maumee River which 
drained glacial Lake Maumee (the basin of the present Lake Erie), The subsequent 
formation of the present Great Lakes, with new watersheds and an eastward drain- 
age, interrupted the former confluences and created a discontinuous distribution 
by isolating some species and preventing the progress of others at different times 
and with varying effectiveness. A striking example of such an obstacle was the 
glacial Grand River whose course transsected the area of the Lower Peninsula; 
after the southern part of that Peninsula had been repopulated with sphaeriids, it 
effectively blocked the northward spread of three species: Pisidium cruciatum, 
P. punctiferum and Sphaerium transversum. likewise, this stream formed the 
southern boundary for P. insigne, which did not enter the Peninsula directly from 
the south, but from the north by more devious routes. The glacial Grand River later 
divided into two streams running in opposite directions, the present easterly- flow- 
ing Saginaw River and the present westerly-flowing Grand River, before P. cruci- 
atum and P. punctiferum could enter the Saginaw drainage from the west. 

The distribution, restricted largely to the Great Lakes bordering the state, 
of P. conventus, P. idahoense and S. nitidum, which are species of deep and cold 
waters, can be explained on an ecological basis; that of P. henslowanum, P. 
amnicum and S. comeum which are restricted to the Great Lakes and their down- 
stream drainage, by their probably only recent importation from Europe. The 
immediate causes for the localized occurrence of various other species or forms 
are, however, less apparent. 

In general it is believed that both active migration during periods of alternate 
flooding and low water levels, which ultimately disrupted previous confluences, as 
well as passive transportation, partly in these waterways by other aquatic animals 
such as crayfishes, frogs and flshes, partly overland by aquatic birds, have ob- 
scured the original distribution of many of the sphaeriids in the inland waters of 
Michigan. The patterns of original distribution are still clearly evident only for 
P. cruciatum, P. punctiferum and S. transversum. , while they are partially 
masked in P.fallax, P. insigne, P. obtusale, P. walkeri and S. fabule. 

INTRODUCTION drainage system. These watersheds com- 

prise Upper (Northern) Peninsula streams 
At present all of the streams of the flowing into (1) Lake Superior and (2) Lake 
six principal watersheds in the two pen- Michigan, and Lower (Southern) Peninsula 

Ínsulas of the State of Michigan belong to streams draining into (3) Lake Michigan, 
the Great Lakes - St. Lawrence River (4) Lake Huron, (5) the St. Clair River, 



iThis investigation was supported (in part) by a 

research grant, 2E-41, from the Nationallnsti- 2present address: Department of Biological 

tute of Allergy and Infectious Diseases, U.S. Sciences, Florida State University, Tallahas- 

Public Health Service. see, Florida, U.S.A. 

(139) 



140 



W. H. HEARD 



Lake St. Clair, and the Detroit River, and 
(6) Lake Erie. The present account of 
the sphaeriids inhabiting Michigan is based 
primarily on the nearly 5000 lots in the 
collections in the Museum of Zoology, 
University of Michigan (UMMZ) from the 
major streams (Table 1) and their con- 
nected lakes in these watersheds. 

The extensive list of 73 species and 36 
varieties of iingernsiil {Sphaerium , includ- 
ing Мм5см/гггш) and pill clams (Pisidiimi) 
recorded for Michigan by Winslow (1926) 
reflects the redundant taxonomy developed 
by Victor Sterki (1916). The present re- 
port reduces that list to 32 species and 
primarily follows the specific nomencla- 
ture of H. B. Herrington (1962); his as- 
sistance with identifications is gratefully 
acknowledged. In addition to good species 
several common "forms" are mentioned. 
These are at present considered to be 
ecological, but since they are incom- 
pletely known they are included here in 
the event that some of them might be 
raised to subspecific or even specific 
rank in the future. The generic and sub- 
generic classification of the Sphaeriidae 
presented here is that which is currently 
accepted by most malacologists. How- 
ever, this classification is much in need 
of critical re-evaluation and will be the 
subject of a future report. 

SYSTEMATIC POSITION OF SPECIES 
AND THEIR DISTRIBUTION 

Species and Habitats 

Subfamily Pisidiinae F. С Baker, 1927 
Genus Pisidum C. Pfeiffer, 1821 

Only the anal siphon developed, the branchial 
siphon either rudimentary or represented by a 
mantle cleft; shell inequipartite: anterior end 
of shell longer than posterior end; beaks occa- 
sionally terminal. 

Q 

Subgenus Neopisidium Odhner, 1921 

Complete absence of branchial siphon and of 
posterior gills; dorsal loop or lobe of the 



TABLE 1. Major streams in the six water 
sheds of Michigan 



WATERSHED 



MAJOR STREAMS 



UPPER PENINSULA 
Lake Superior 



Lake Michigan 



LOWER PENINSULA 
Lake Michigan 



Lake Huron 



St. Clair River 
Lake St. Clair 
Detroit River 

Lake Erie 



Ontonagon River 
Sturgeon River 
Tahquamenon River 

Menominee River 
Ford River 
Escanaba River 
Manistique River 

Manistee River 
Muskegon River 
Grand River 
Kalamazoo River 
St. Joseph River 

Cheboygan River 
Thunder Bay River 
Au Sable River 
Saginaw River 

Black River 
Belle River 
Clinton River 
River Rouge 

Huron River 
River Raisin 
St. Joseph River of 
the Maumee River 



nephridia united; constant retention of juvenile 
characters. 

Pisidiiim conventus Clessin. The cir- 
cumpolar P. conventus i^^byssorut)! Sterki) 
occurs in the Great Lakes (Lakes Su- 
perior, Michigan, and Ontario; Heard, 
1962) and in the deep cold lakes of Isle 
Royale, an island in Lake Superior. 

Pisidiuni criiciatum Sterki (Fig. 2). 
This minute sphaeriid (usually less than 
2.0 mm in length) is known only from the 
lower portions of the Grand River (Ottawa 
and Kent Counties) and from the River 
Raisin and its tributaries (Washtenaw 
County) . An explanation of this peculiar 
distribution is attempted in the section 
on Routes of Dispersal. 

Pisidiiim insigne Gabb (Fig. 3). A rare 
sphaeriid found in lakes, ponds, bogs, and 



ЗтЬе morphology of Pisidium cruciatum Sterki and P. insigne Gabb is incompletely known. How- 
ever, preliminary observations suggest that both species are members of Neopisidium , and they 
are placed here provisionally. 



SPHAERIID DISTRIBUTION IN MICHIGAN 



141 



QUEBEC 




Fig. 1. Present drainage pattern in Mchigan and surrounding areas. 



Streams, P. insigne is absent from the 
southern drainages of the Lower Penin- 
sula. 

Pisidium punctiferum (Guppy) (Fig. 2). 
The disjunct distribution of this sphaeriid 
in Michigan (i.e., Brown Lake, Dickinson 
County (Baker, 1922) and the North Branch 
of the Paint River, iron County, in the 
Lake Michigan watershed of the Upper 
Peninsula, and the lower Grand River in 
Ottawa and Kent Counties in the western 
part of the Lower Peninsula) will be dis- 
cussed later under Routes of Dispersal. 



Subgenus Eupisidium Odhner, 1921 

Partially fused mantle slit containing a short 
slit representing the branchial siphon; small 
posterior gills present in addition to larger 
anterior gills; posterior gills with inner lamel- 
lae only (outer lamellae entirely lacking); dorsal 
loop or lobe of the nephridia cleft. 

Pisidium adamsi Prime. This com- 
mon species occurs in the state of Michi- 
gan as the typical P. adamsi and as the 
form sargenti Sterki. Both types are 
more representative of lakes than streams , 



142 



W. H. HEARD 



Pisidium aequilaterale Prime. "... 
reported from Michigan and northward 
and westward, but I have seen no speci- 
ments from these regions" (Sterki, 1916). 
This species is typically found in the 
northeastern United States (Herrington, 
1962). However, reliable records for 
Michigan are lacking. Although I have 
examined three different lots of P. aequi- 
laterale from museum collections label- 
led Reed's Lake, Grand Rapids, Kent 
County, Michigan, the validity of this 
locality record must be subject to ques- 
tion because many other Grand Rapids 
citations are quite obviously mislabeled 
(some even include marine species) . It 
would seem that, in the active exchange 
of samples conducted by the early na- 
turalists, certain lots were tagged with 
the addresses of the sender and not the 
true place of origin. 

Pisidium casertanum (Poli). The most 
common and widespread sphaeriid in the 
state, this variable species is composed 
of several dozen forms from a wide range 
of habitats: lakes, ponds, bogs, swamps, 
temporary woods pools, beach pools, and 
streams of all sizes. 

Pisidium compressum Prime. Also of 
widespread range, this species is com- 
mon in lakes and streams of all sizes. 
Specimens from streams usually exhibit 
a pronounced diagonal ridge on the beaks; 
shells from lakes are stunted, have an 
atypical shape, and the ridge is incon- 
spicuous if it is present at all. Several 
forms are represented in the state: P. 
compressum arrosum Sterki (streams), 
P, c. confer turn Sterki (lakes), P. c. lae- 
vigatum. Sterki (a very common form in- 
habiting both lakes and streams), P. c. 
pellucidum Sterki (primarily a stream 
form), and P. с rostratum Sterki (lakes). 

Pisidium fallax Sterki. P. fallax oc- 
curs throughout the Lower Peninsula but 
is found only in the Lake Michigan water- 
shed of the Upper Peninsula. More com- 
monly found in streams than lakes, this 
species frequently exhibits tubercular 
beaks, a feature in which the beaks appear 
to have been pushed down, creating a con- 
centric pseudo -ridge or bar at their base. 



Pisidium ferrugineum Prime. Rarely 
taken in quantity, P. ferrugineum and 
its form medianum Prime are typically 
inhabitants of standing waters. This spe- 
cies occurs throughout the state. 

Pisidium hensloivanum (Sheppard). Pre- 
sumably introduced from Europe, this 
sphaeriid is restricted to the Great Lakes 
in Michigan and occurs more abundantly 
in the lower lakes. Its presence as far 
inland as Lake Erie is well documented. 
Its extended range has been recorded for 
Lake Michigan (Heard, 1961), and recent 
dredging by Dr. Frank F. Hooper, Insti- 
tute for Fisheries Research, University 
of Michigan, has also turned up living 
animals of P. henslowatium from Saginaw 
Bay of intervening Lake Huron. 

Pisidium lilljeborgi Clessin. Predomi- 
nently a lake dweller, this species ranges 
widely in Michigan and occurs only in- 
frequently in streams. The typical P. 
lilljeborgi is found in all drainages but 
the Lake Michigan watershed of the Upper 
Peninsula; the form cristatum Sterki does 
not inhabit the southern streams of the 
Lower Peninsula. 

Pisidium milium Held. This species 
is uncommon but has a wide range. It 
inhabits lakes and small streams in all 
watersheds. 

Pisidiwu nitidum Jenyns. Typically 
occupants of lakes, P. nitidum and the 
form paupercidum Sterki occur through- 
out Michigan. However, the form contor- 
tiim Sterki is found only in the Muskegon, 
Saginaw and Rouge drainages of the Lower 
Peninsula. 

Pisidium obtusale C.Pieiiier. This fre- 
quently globular species is found through- 
out the state, inhabiting lakes, ponds, and 
sluggish, protected areas of streams. 
The typical P. obtusale, however, is ab- 
sent in the Northern Peninsula where it 
is replaced by the forms rotwidatum 
Prime and ventricosum Prime, the for- 
mer occuring only in the Lake Michigan 
watershed and the latter only in the Lake 
Superior watershed. 

Pisidium subtnmcatum Malm. A spe- 
cies found in few but widespread locali- 
ties, P. subtruncatum occurs in all 



ЗРНАЕШШ DISTRroUTION IN MICHIGAN 



143 




Fig. 2. The distribution of Pisidium (Neopisidium) cruciatum ала Pisidium (Neopisidium) 
punctiferum in Michigan. 



144 



W. H. HEARD 




Flg. 3. The distribution of Pisidium (Pisidium) dubium and Pisidium (Neopisidium) insigne 
in Michigan. 



SPHAERIID DISTRIBUTION IN MICIDGAN 



145 




Fig. 4. The distribution of Pisidium (Pisidium) idahoense and Sphaerium transversum in 
Michigan. 



146 



W. H. HEARD 



Michigan watersheds, inhabiting lakes 
and small streams. 

Pisidiwn variable Prime. This spe- 
cies is commonly encountered in all state 
watersheds in both lakes and streams. 

Pisidium walkeri Sterki. Occupying 
lakes and streams throughout the Lower 
Peninsula, P. walkeri and its form mai- 
nense do not occur in the Upper Penin- 
sula. 

Subgenus Pisidium s.s. C. Pfeiffer 

Branchial siphon rudimentary (P. dubium) or 
represented only by a slit in the partially fused 
mantle (P.amnicum and P. idahoense); large 
posterior gills present in addition to large an- 
terior gills; posterior gills with inner lamellae 
as well as outer lamellae; dorsal loop or lobe 
of nephridia cleft, 

Pisidium amnicum (Mnller) . This large 
species (length greater than 5 mm) is 
known only from certain waters bordering 
the state in the east: Lake Erie, the De- 
troit River, and Saginaw Bay of Lake 
Huron. Introduced from Europe and at 
present common only in the Great Lakes - 
St. Lawrence River drainage, P. amnicum 
has advanced into Lake Huron and may 
eventually extend its range upstream into 
Lake Michigan, as did P. henslowanum , 
and possibly into Lake Superior. 

Pisidium dubium (Say) (Fig. 3). Typi- 
cally living in very small colonies, this 
widespread species is rarely found in 
lentic habitats. Its large size (length 
more than 5 mm) may lead to some con- 
fusion with P. amnicum and P. idahoense . 
However, the coarse striae of P. dubium 
are absent from the beaks while remain- 
ing prominent in P. amnicum; the striae 
in P. idahoense are fine. In addition the 
beaks are more terminal in P. dubium, 
and the hinge teeth are different from 
those of the two other species as de- 
scribed in detail by Herrington (1962). 

Pisidium idahoense Roper (Fig. 4). 
This large species (length greater than 
5 mm; see P. dubium) is typical of cold 
and deep waters such as Lake Superior 
and Lake Michigan (Heard, 1962), although 
it occurs as well in suitable ''inland" 
localities: Isle Royale (Lake Superior), 



Keweenaw County; Sturgeon River and 
Douglas Lake, Cheboygan County: Hunt 
Creek, Ogemaw County; Bass Lake, Li- 
vingston County. 

Subfamily Sphaeriinae F. С Baker, 1927 
Genus Sphaerium Scopoli, 1777 

A distinct anal and branchial siphon present, 
either fused only at their base or for the greater 
part of their length; shell nearly equipartite, 
anterior end of shell shorter than posterior end, 

Sphaerium corneum (Linnaeus). An- 
other sphaeriid introduced from Europe 
and restricted to the lower Great Lakes - 
St. Lawrence drainage, S. corneum is 
presently found only in waters outside the 
boundaries of the state: Lake Erie. 

Sphaerium f abale Prime. This species 
is very widespread in the streams of the 
Lower Peninsula watersheds but does not 
occur in the Northern Peninsula. 

Sphaerium lacustre (Müller). Although 
the typical S, lacustre ranges throughout 
all watersheds of Michigan, the form 
ryckholti (Normand) is not found south of 
the Grand- Saginaw Valley, while the form 
jayense (Prime) does not occur north of 
it. 

Sphaerium nitidum Clessin. Typical of 
deep and cold waters, S, nitidum occurs 
in Lake Michigan and Lake Huron, and 
the inland lakes of Isle Royale (Lake 
Superior) in Keweenaw County (Heard, 
1961). 

Sphaerium occidentale (Prime) . A char- 
acteristic part of the fauna of woods 
pools, S. occidentale ranges throughout 
Michigan. 

Sphaerium partumeium (Say) (Fig, 5). 
This species is very widespread in tem- 
porary woods ponds and muddy substrates 
of lakes and sluggish streams of Michi- 
gan. 

Sphaerium rhomboideum (Say) (Fig. 6). 
Of wide range in all Michigan watersheds, 
this peculiar species, which has a rhom- 
boid shape, inhabits muddy areas in lakes 
and streams. 

Sphaerium securis (Prime). Widely 
ranging throughout the state, S. securis 
is found in lakes and ponds with muddy 
substrate, swamps, and woods pools. 



SPHAERIID DISTRIBUTION IN MICHIGAN 



147 



Sphaerium striatinum (Lamarck) . This 
variable species is the most commonly 
encountered of all the sphaeria in the 
state. It has many forms which are found 
in lakes and streams of all sizes. 

Sphaerium sulcatum (Lamarck). This 
is one of the largest of all sphaeriids, 
sometimes reaching one inch in length. 
It has a more rectangular shape and more 
consistent striae (in spacing and height) 
than S. striatinum with which it is fre- 
quently associated. Although S. sulcatum 
includes several forms, it is considerably 
less variable than most sphaeriid clams. 
It occurs commonly in lakes and streams 
throughout Michigan. 

Sphaerium transversum (Say) (Fig. 4). 
This sphaeriid occupies streams rather 
than the usual habitats of its more closely 
related fellow species, i.e., S. lacustre, 
S. partumeium and S. securis. In Michi- 
gan S. transversum occurs only in the 
southern streams of the Lower Penin- 
sula. 



Distribution Patterns 

In summary, a review of the locality 
records available to me reveals that the 
Sphaeriids in Michigan fall into two cate- 
gories: species of general distribution 
of which 3 representatives have been 
mapped, and species with a restricted 
range. 

Sphaeriids with general distribution 
(1. e. , found in all watersheds of both 
peninsulas) are, as follows: 

Pisidium adam s i 

P. casertanum and its forms 

P. compre ssum 

P. dubium (Fig. 3) 

P. ferrugineum 

P. milium 

P. nitidum s.S. and form pauperculum 

P. subtruncatum 

P. variabile 

Sphaerium lacustre s.s. 

S. occidentale 

S. partumeium (Fig. 5) 

S. rhomboideum (Fig. 6) 

S. securis 

S. striatinum 

S. sulcatum 



The sphaeriid species or "forms" with 
restricted range can be grouped into the 
following categories: 

(a) Species present in all drainages 
except '(1) the Lake Superior Water- 
shed of the Upper Peninsula in the 
very north: P.fallax and P.ob- 
tusale s.S. -wiihiis iormrotwidatiim, 
or except (2) the Lake Michigan 
Watershed of that Peninsula: also 
P. obtusale s.s. and its form ven- 
tricosum, and P. lilljeborgi. 

(b) Species of northern ocurrence, ab- 
sent only from the southern drain- 
ages of the Lower Peninsula: P. 
insigne (Fig. 3); also P. lilljeborgi 
form cristatuma.nd S . lacustre form 
ryckholti. 

(c) Species restricted to the Lower Pen- 
insula: P. walkeri, S.fabale and P. 
obtusale s.s. which are found gen- 
erally throughout the Lower Penin- 
sula, and P. cruciatum (Fig. 2), S. 
transversum (Fig. 4), P. nitidum 
form contortum and S. lacustre form 
jayense which occur only in the 
southern drainages of this peninsula, 
south of the Grand-Saginaw Valley. 

(d) Species occurring only in water- 
sheds draining into Lake Michigan 
from both the Upper and Lower 
Peninsulas: P. punctiferum and its 
forms (Fig. 2). 

(e) Species common to the Great Lakes 
bordering the State: P. amnicum, 
P. henslowanum and S. corneum. 
Pisidium conventus and S. nitidum. 
are also characteristic of the Great 
Lakes and in addition occur in cer- 
tain lakes on Isle Royale in Lake 
Superior. Pisidium idahoense is 
typical of these habitats and also 
persists in highly localized relict 
populations in a few inland lakes 
and streams in the Lower Penin- 
sula (see Fig. 4). 

The observed distribution for both spe- 
cies and forms can, to a certain extent, 
be explained by habitat requirements and 
particularly by the post-glacial history of 
the territory and the paths of invasion 
that were used by these and other fresh 
water clams, as discussed below. 



W. H. HEARD 




♦ , *^-. 



Ф SPHAERIUM PARTUMEIUM 







Fig. 5. The distribution of Sphaerium partumeimn in Michigan. 



SPHAERiro DISTRroUTION IN MICHIGAN 



149 




Fig. 6. The distribution of Sphaerium rhomboideum in Michigan. 



150 



W. H. HEARD 



ROUTES AND MEANS OF DISPERSAL 

General effect of former Drainage 
Confluences 

Glaciation in the Great Lakes region 
not only created a large number of lentic 
and lotie habitats, but the subsequent 
formation of the present drainage basins 
played an instrumental role in the spread 
of numerous aquatic mollusks. When the 
peculiar distribution patterns of certain 
Michigan sphaeriids are considered, one 
can find in the patterns a reflection of 
the original drainage basins and evidences 
of some of the later changes in them. 
Fresh water clams were able to migrate 
from one drainage to another during peri- 
ods of glacial confluence. Low water 
levels, following the retreat of the gla- 
ciers, interrupted many of these drainage 
systems so that (1) barriers to further 
migration were created and (2) some 
faunal elements were isolated. 

The relation of the distribution of 
unionids or naiades to the post-glacial 
history of Michigan has been studied by 
several investigators. The major avenues 
of northward migration into this region 
from the Mississippi River drainages 
were outlined by Walker (1898, 1913), 
Ortmann (1924), van der Schalie (1938, 
1945) and Goodrich and van der Schalie 
(1939). The three major routes that served 
for the dispersal of mussels were evi- 
dently also used by the sphaeriid clams. 
Briefly they are (Fig. 7): (a) the Illinois- 
Des Plaines outlet of glacial Lake Chi- 
cago (the present Lake Michigan), (b) the 
Maumee River, draining Lake Maumee 
(the present Lake Erie), which served for 
the colonization of the Lower Michigan 
Peninsula from the east, and (c) the Fox 
River Valley in eastern Wisconsin, which 
served as a path of entry into the Upper 
Peninsula. After these pelecypods suc- 
cessfully invaded Michigan waters, the 
confluences between the Mississippi and 
Great Lakes drainages were eventually 
broken and further dispersal of certain 
species was prevented by the formation 
of certain other barriers, such as the 
glacial Grand River, discussed below. 



^ с 



Fig. 7. Migratory routes of sphaeriid clams into 
Michigan, a: the Fox PU ver Valley In 
eastern Wisconsin; b: the Illinois— Des 
Plaines drainage of glacial Lake Chicago; 
c: the Maumee River draining glacial 
Lake Maumee. The extent of glacial ice 
cover Is indicated by stippling, and the 
present Great Lakes are shown by slant- 
ing lines. 

The relationship between present day hy- 
drographical patterns in the Great Lake 
area and those of post-glacial times can 
be seen by comparing Figs. 1 and 7, and, 
for greater detail in the Fox River Val- 
ley, Fig. 8. 



Routes of Penetration 

The role of the Illinois -Des Plaines 
outlet of Glacial Lake Chicago and the 
Maumee River draining glacial Lake 
Maumee . The interpretation of the marked 
similarity of the Mississippi naiad fauna 
with that of the central Great Lakes is 
based on the direct connection, already 
referred to, of glacial Lake Chicago (the 
present Lake Michigan) and glacial Lake 
Maumee (the present Lake Erie) with the 
Mississippi drainage during the Pleisto- 
cene Epoch. 

The same explanation may be used to 
interpret the distribution of certain 



SPHAERIID DISTRIBUTION IN MICHIGAN 



151 




Fig. 8. The present drainage systems in the Fox 
River Valley in eastern Wisconsin, a: the 
Wisconsin River, still in the Mississippi 
River drainage; b: the Fox River, now in 
the Great Lakes drainage; c: Lake 
Winnebago; d: the Menominee River in 
the Upper Peninsula of Michigan. The 
Mississippi River drainage is indicated 
by stippling. 

sphaerlids in Michigan, particularly that 
of the very localized species Pisidimn 
cruciatum, Sphaerium trans version, as 
well as of Pisidium punctiferiim s.s. and 
its form armatum Sterki, which are re- 
stricted to the southernmost drainages 
of the Lower Peninsula and whose fur- 
ther advance was quite evidently blocked 
by geographical changes. 

Examination of museum specimens and 
of the literature (Sterki, 1895, 1916; Her- 
rington, 1962) reveals that Pisidium cru- 
ciatum presently inhabits streams of the 
extensive Mississippi River drainage sys- 
tem and two Michigan streams, the Grand 
and Raisin Rivers (Fig. 2), which are 
tributaries of the Great Lakes - St. Law- 
rence River drainage. This pattern is 
similar to the discontinuous distribution 



observed among several unionids. 

Pisidium cruciatum reached the lower 
regions of the Grand River through the 
Illinois-Des Plaines drainage, and gained 
access to the River Raisin through the 
glacial Maumee River. The River Raisin 
evidently flowed directly into the Maumee 
at that time (van der Schalle, 1938). 

Sphaerium trans ver sum {Fig. 4) oc- 
curs in Michigan only in the Lower Pen- 
insula south of the glacial Grand River 
Valley, but ranges a little farther north 
in Wisconsin (Baker, 1928) and much 
farther north in Canada (Great Slave Lake; 
Herrington, 1950). This species also 
reached Michigan through the Illinois-Des 
Plaines and Maumee River channels. Its 
northward spread in Michigan was blocked 
by the glacial Grand River barrier (see 
below), and in Wisconsin by the rupture 
of the glacial Fox River and subsequent 
stream -capture of part of this stream by 
the Great Lakes-St. Lawrence drainage 
system. 

Pisidimn punctiferum s.s. and P.p. 
form armatum Sterki (Fig. 3) are local- 
ized in Michigan in the lower reaches of 
the Grand River, a colonization which may 
again be interpreted as post-glacial in- 
vasion through the Illinois-Des Plaines 
drainage. 

Role of the Fox River Valley. During 
the late Wisconsin stage of glaciation the 
Mississippi (Wisconsin River) and Great 
Lakes drainages (the present Fox River 
and Green Bay) were also connected 
through the Fox River channel in eastern 
Wisconsin (Goodrich and van der Schalle, 
1939), and this route was employed by 
many of the species of sphaeriids pres- 
ently inhabiting the Upper Peninsula of 
Michigan. The present drainages of this 
former confluence are shown in Fig. 8. 
The sphaeriids of Wisconsin (Baker, 1928; 
Morrison, 1932) and of the Lake Michigan 
Watershed of the Upper Peninsula are 
compared in Table 2. Most sphaeriids 
are found throughout the remnant drain- 
ages of the glacial Fox River confluence, 
although there are some significant ex- 
ceptions. 

Baker's (1928) records of P. punctiferum 



152 



W. H. HEARD 



TABLE 2. Sphaeriids of the Fox River Valley in eastern Wisconsin and the Lake Michigan 

Watershed of the Upper Peninsula of Michigan. The records from the present Fox River 

drainage include those from Lake Winnebago (see Fig. 3) 





MISSISSIPPI DRAINAGES 


GREAT LAKES DRAINAGES 


SPECIES 






















Wisconsin 


Fox 


Lake Michigan 




Mise. Drainages 


River 


River 


Watershed 


Pisidium 










adamsi 


X 


X 


X 


X 


casertanum 


X 


X 


X 


X 


compressum 


X 


X 


X 


X 


cruciatum 


X 








dubium 




X 


X 


X 


fallax 


X 




X 


X 


ferrugineum 


X 


X 


X 


X 


idahoense 


X 




X 




insigne 








X 


lilljeborgi 


X 


X 


X 




milium 






X 


X 


nitidum 


X 


X 


X 


X 


ob túsale 


X 




X 


X 


pune ti/e rum 


X 


X 


X 


X 


variabile 


X 


X 


X 


X 


walke ri 






X 




Sphaerium 










lacustre 


X 




X 


X 


occidentale 


X 


X 


X 


X 


partumeium 


X 


X 


X 


X 


rkomboideum 


X 


X 




X 


securis 


X 


X 




X 


striatinum 


X 


X 


X 


X 


sulcatum 


X 


X 


X 


X 


trans ver sum 






X 





form simplex Sterki in Lake Winnebago 
and the Fox River drainage lend support- 
ing evidence for the former existence of 
a migratory route through eastern Wis- 
consin into the Upper Peninsula of Mich- 
igan. This form has a restricted range 
in Michigan (Fig. 2) occurring only in the 
Lake Michigan drainage of the western 
end of the Upper Peninsula (Baker 1922; 
UMMZ specimens), where it was isolated 
after rupture of the Fox River confluence. 
Conversely, the northward progress from 
Wisconsin into the Upper Peninsula of 3 
other species was presumably arrested 
when the Fox River confluence was broken: 
Pisidium cruciatum failed to enter the 
present Great Lakes (Lake Michigan) 
drainage, while P.ivalkeri and Sphaeriwn 
transversum passed into the Fox River 



of the Great Lake drainage, but as yet 
have failed to populate the Upper Penin- 
sula. Two other species appear to have 
a discontinuous distribution in this hydro- 
graphical area: Pisidium insigne, which 
is found in the Upper Peninsula of Mich- 
igan, has not yet been recorded from 
Wisconsin, but will probably be found 
there after more intensive collecting. 
Pisidum lilljeborgi, although present in 
the Wisconsin and Fox drainages of Wis- 
consin and the Lake Superior Watershed 
of Michigan, is not known from the Lake 
Michigan Watershed of the Northern 
Peninsula, but is likely to be discovered 
in these drainages with further collect- 
ing. 

The routes used by those species or 
forms that seem to have invaded Michi- 



SPHAERIID DISTRIBUTION IN MICHIGAN 



153 



gan from the north are not accurately 
known. An extension of the Fox River 
Valley route would, however, explain 
the distribution of Pisidium insigne, P. 
lilljeborgi form cristatiim and Sphaerium 
lacustre form ryckholti which do not 
occur in the southern part of the Lower 
Peninsula, These species evidently did 
not penetrate the Lower Peninsula through 
the Illinois -Des Plaines or Maumee 
routes, but were presumably able to mi- 
grate through the Fox River Valley, 
colonize the Upper Peninsula, and pass 
southward into the northern area of the 
Lower Peninsula. 



Barriers: Effect of the Glacial 
Grand River 

During the Pleistocene Epoch, the lower 
peninsula of Michigan was transsected by 
the glacial Grand River (Bretz, 1953) 
which channeled the waters of the Erie 
and Huron basins through the Grand-Sagi- 
naw Valley into glacial Lake Chicago 
(Hough, 1958). The present remnants of 
this glacial stream are the Grand River, 
flowing westward into Lake Michigan, and 
the Saginaw River, draining northeastward 
into Saginaw Bay of Lake Huron. Walker's 
(1898) Zoogeographie study of the unionid 
clams of Michigan revealed that the great 
majority of species are essentially con- 
fined to the Grand-Saginaw Valley and to 
the streams south of it. In contrast, how- 
ever, the Grand-Saginaw Valley was a bar- 
rier to only a few sphaeriids (3 species 
and 3 forms), as most species (18 spe- 
cies, including 6 forms) exhibit a general 
range throughout the state. The highly 
varied assemblage of sphaeriid clams 
occupying the Grand and Saginaw River 
drainages is presented in Table 3. 

Pisidium cruciatum , Sphaerium lacustre 
îorm jayense and S. transuersum do not 
extend north of the Grand-Saginaw drain- 
ages. S. lacustre s.S., has a general 
range in North America; in Michigan, 
however, the form jayense is not found 
north of the Grand-Saginaw Valley. 



TABLE 3. Sphaeriidae of the Grand - Saginaw 
Valley, Michigan^ 



Species 



Grand 
River 



Saginaw 
River 



Pisidium 

adamsi Prime 

form sargenti Sterki 
casertanum (Poli) 

f. roperi Sterki 
compressum Prime 
cruciatum Sterki 
dubium (Say) 
fallax Sterki 
ferrugineum Prime 

f. medianum Sterki 
insigne Gabb 
lilljeborgi Clessin 
milium Held 
nitidum Jenyns 

f. contortum Prime 

f. pauperculum Sterki 
obtusale C. Pfeiffer 

f. rotundatum Prime 

f. ventricosum Prime 
punctiferum (Guppy) 

f. armatum Sterki 
variabile Prime 
walke ri Sterki 

f . ' mainense Sterki 
Sphaerium 
fabale Prime 
lacustre (Müller) 
occidentale Prime 
partumeium (Say) 
rhomboideum (Say) 
securis Prime 
striatinum (Lamarck) 
sulcatum (Lamarck) 
transversum (Say) 



X 


X 


X 




X 


X 


X 


X 


X 


X 


X 




X 


X 


X 


X 


X 


X 


X 


X 


X 




X 


X 


X 




X 


X 




X 


X 


X 


X 




X 


X 


X 


X 


X 




X 




X 


X 


X 


X 


X 


X 


X 


X 


X 


X 


X 




X 


X 


X 


X 


X 


X 


X 


X 


X 


X 


X 


X 



The Grand-Saginaw Valley also forms 
the southern boundary of the distribution 
of Pisidium insigne, P. lilljeborgi form 
cristatum and Sphaerium lacustre form 
ryckholti. Examination of broader range 
patterns reveals that P. insigne has a 
naturally northern occurrence. P. lillje- 
borgi s.S., also a northern species, oc- 
curs throughout Michigan except in the 
Lake Michigan watershed of the Upper 



^Pisidium lilljeborgi i. cristatum Sterki and 
Sphaerium lacustre f. ryckholti (Normand) are 
foimd only north of the Valley, and Sphaerium 
lacustre f, jayense Prime occurs only south 
of it. 



154 



W. H. HEARD 



Peninsula; only the form cristatum has a 
limited range in the Lower Peninsula. 

From the material at hand, it would 
seem that several more species and 
forms inhabit the Grand River than oc- 
cur in the Saginaw River. It is however 
suspected that further collecting in the 
Saginaw Valley might also reveal the 
presence of the more widespread species 
Pisidium insigne and P. milium; P. crii- 
ciatiim and P. punctiferum, of limited 
range, probably do not occur there. 
Should their absence be confirmed, this 
distribution pattern would indicate that a 
rupture in a single drainage creates an 
effective barrier to dispersal; i.e., that 
glacial Grand River must have given rise 
to the easterly -flowing Saginaw River be- 
fore P. cruciatum and P. punctiferum 
were able to populate this area from the 
west. 

Means of Dispersal 

It has often been suggested that various 
aquatic animals are responsible for the 
dispersal of sphaeriid clams. Among 
these are various aquatic insects (Kew, 
1893; Fernando, 1954), crayfishes (Kew, 
1893), fishes (Odhner, 1951), frogs, sala- 
manders and aquatic birds (Kew, 1893). 
Published accounts of sphaeriids attached 
to the exterior of other aquatic and ter- 
restrial animals indicate that the spread 
of these bivalves is linked to the move- 
ments and dispersal of their transport 
hosts, i.e., largely to the water connec- 
tions. Odhner (1951) also mentioned the 
possibility of endozoic dispersal: unborn 
juveniles, protected in the gills within the 
shell of the parent, may occasionally be 
able to pass through the intestine of a 
fish without injury. Such a mode of dis- 
persal is still dependent on the move- 
ments of the host animal in the water- 
ways. 

While overland carriage as a means of 
dispersal of sphaeriid clams is not alto- 
gether discounted, it is relegated to a 
secondary role. It seems reasonable to 
assume that the distribution of sphaeriids 
was originally accomplished by active 



migration through confluent drainage pat- 
terns. Transportation by other animals 
has doubtlessly followed and in most cases 
has effectively masked the original dis- 
tribution patterns. The original distribu- 
tion patterns of P. cruciatum, P. puncti- 
forum, S. transversum and S. lacustre 
form jayense in Michigan are still clearly 
discernible, those of P.fallax, P. insigne, 
P. walkeri, P. lilljeborgi form cristatum, 
P. obtusale s.s. and its forms rotundatum 
2iná ventrico sum, S.f abale, and S. lacustre 
form ryckholti are evident to a lesser 
degree, while passive dispersal has pre- 
sumably disguised to varying extents the 
original ranges of the remaining species 
and forms. 



DISCUSSION 

It must be understood that not all 
species disperse at the same time or at 
the same rate. The same obstacles may 
not exist at ail times and the same ob- 
stacle may be overcome by some species 
but not by others in a given period of 
time. While Pisidium, obtusale s.S., P. 
ivalkeri and Sphaerium /abale, for exam- 
ple, presently extend throughout the Lower 
Peninsula of Michigan, P. cruciatum , P. 
punctiferum and S. transversum have not 
as yet been able to spread north of the 
Grand-Saginaw Valley (either by active 
migration or through adventitious trans- 
port by other animals), and P. insigne, 
present in the north, is still absent from 
the region of Michigan south of that Valley. 

The geographical range of a species is 
also confined by the limitations imposed 
by the ecological tolerances of the ani- 
mals. Thus, dispersal takes place not 
only through time but also through an 
ecological continuum in space. Pisidium 
idaJioense is infrequently found south of 
the North American Great Lakes and is 
only rarely found "inland" from the Great 
Lakes in that area. The disjunct inland 
localities of P. idahoense in Michigan 
may represent suitable habitats which 
have persisted locally, enabling relict 
populations to survive. 

Pisidium fallax presumably migrated 



SPHAERIID DISTRIBUTION IN MICHIGAN 



155 



through the glacial Fox River Valley (see 
Routes of Dispersal) into the Lake Michi- 
gan Watershed of the Upper Peninsula 
which is easiest of access from the Fox 
River, but it was apparently unable to 
invade and populate the Lake Superior 
Watershed, The apparent absence of P. 
ivalkeri from the entire Upper Peninsula 
is unexpected, for Baker (1928) reports 
this species to inhabit the Fox River 
drainage and other localities in eastern 
Wisconsin. Comparing the distribution of 
other pisidia, one would expect that P. 
ivalkeri also migrated from the Missis- 
sippi River drainage through the Fox 
River Valley into the Upper Peninsula 
(see Role of Fox River Valley). Further 
collecting in the Lake Michigan Water- 
shed, may reveal the presence of the 
species in that area. 

A surprisingly extensive sphaeriid fauna 
is localized in the waters of the Isle 
Royale, and island in northern Lake Su- 
perior (Walker, 1909; UMMZ specimens) 
which is much larger than that found in 
the Lake itself (Heard, 1962): 

Pisidiwn adamsi 

P. casertanum 

P. conventus 

P. ferriigineum 

P. idahoense 

P. lilljeborgi 

P. milium 

P. nitidum 

P. ob túsale 

P. punctiferum? 

P. subtnmcatum 

P. variabile 

Sphaerium nitidum 

S. securis 

S. sulcatum. 
This assemblage represents an isolated 
segment of the fauna of the ''mainland" of 
Ontario, Canada. The routes by which 
these sphaeriids colonized Isle Royale 
are not accurately known. Presumably 
they migrated to the island from western 
Ontario after having passed northward up 
the Mississippi River, bypassing the Fox 
River Valley outlet, and around the basin 
of the present Lake Superior. 

On the whole, the Michigan sphaeriid 



fauna cannot yet be adequately correlated 
with that of surrounding territories be- 
cause records for these areas are only 
fragmentary. 

The apparent absence of species and 
forms from individual watersheds may be 
due to the lack of sufficient collecting in 
those areas. This is expected to apply 
to P. lilljeborgi s.S., a species presently 
unknown in Michigan only from the Lake 
Michigan Watershed of the Upper Penin- 
sula, yet common throughout eastern Wis- 
consin. It is anticipated that with more 
intensive collecting it will be found in the 
Lake Michigan Watershed of the Upper 
Peninsula because this drainage system 
must have been utilized in populating the 
Lake Superior Watershed from the Fox 
River. Pisidium insigne is widespread 
in both watersheds of Michigan's Upper 
Peninsula but has not been recorded from 
Wisconsin at all. It, too, will probably 
be discovered in eastern Wisconsin 
throughout the Wisconsin and Fox drain- 
ages of the Fox River Valley migratory 
route . 

The peculiar distribution of "forms" 
of certain species (see Distribution Pat- 
terns) is difficult to interpret. It is fre- 
quently found that the typical species has 
a different distribution than its forms as 
shown below for P. lilljeborgi and P. 
ob túsale. 

Pisidium lilljeborgi s.s. is more com- 
mon in eastern Wisconsin (the Fox River 
Valley migratory route) and occurs 
throughout Michigan's Upper and Lower 
Peninsulas (being expected in the Lake 
Michigan Watershed of the Upper Penin- 
sula, as previously mentioned). The form 
P. I. cristatwn is widely distributed in 
Wisconsin, occurs over the Upper Penin- 
sula, and penetrates only into the northern 
portions of the Lower Peninsula of Michi- 
gan. 

The typical P. obtusale has not been 
recordedfor either Wisconsin or the Upper 
Peninsula of Michigan but is common in 
the Lower Peninsula and is present on 
Isle Royale (Lake Superior). Baker (1928) 
reports two widely separate localities for 
the form P. o. rotundatum in Wisconsin, 



156 



W. H. HEARD 



whose hydrographie al connections cannot 
be determined. In Michigan the form ro- 
timdatimi is found over the Lower Penin- 
sula and replaces the typical P. obtusale 
in the Lake Michigan Watershed of the 
Upper Peninsula. The form P. o. ventri- 
cosum is not listed for Wisconsin but 
occurs throughout the Lower Peninsula 
and the Lake Superior Watershed of the 
Upper Peninsula of Michigan. The com- 
mon Wisconsin form is P. o. vesiculare 
which Baker (1928) states to occur in the 
eastern part of the State. 

The number of so-called "forms" with 
limited range in a distribution pattern 
parallel to the geological history of the 
area raises the question of whether these 
forms are not really true subspecies (i.e., 
geographical varieties) which arose before 
the present distribution of their parent 
species was determined or which have 
appeared згисе the formation of the pres- 
ent drainage systems and subsequent es- 
tablishment of a restricted range for the 
parent species (or are appeariiig non). 
Unfortunately, too little is known con- 
cerning the overall distribution and gen- 
eral biology of sphaeriid clams (both 
species and "forms") to permit further 
conjecture at the present time. It is 
hoped, however, that this report will serve 
to stimulate other attempts to define the 
distribution and Zoogeographie al relation- 
ships of the Sphaeriidae. 

LITERATURE CITED 

BAKER, F.C., 1927, On the division of the 

Sphaeriidae into two subfamilies; and the 

description of a new genus of Unionidae, 

with descriptions of new varieties. Amer. 

Midi. Nat., 10(7):220-223. 
, 1928, The fresh water Mollusca of 

Wisconsin, II. Pelecypoda, Wise. Geol. Nat. 

Hist. Surv. Bull. 70, 482 p. 
BAKER, H. В., 1922, The Mollusca ofDicklnson 

County, Michigan, Occ. Pap. No. Ill, Univ. 

Mich. Mus. Zool. , 44 p. 
BRETZ, J. H., 1953, Glacial Grand River, 

Michigan. Pap. Mich. Acad. Sei., Arts and 

Lett., 38:359-382. 
FERNANDO, C. H., 1954, The possible dispersal 

of Pisidium by Corixidae. J. Conchol. ,24(1): 

17-19. 
GOODRICH, CandH. VAN DER SCHAUE, 1939, 



Aquatic moUusks of the Upper Peninsula of 
Michigan. Misc. Publ. No. 43, Univ. Mich. 
Mus. Zool., 45 p. 

HEARD, W. H., 1961, Pisidium henslowanum 
(Sheppard) in Lake Michigan. Nautilus, 
74(3):123. 

, 1962, The Sphaeriidae (Mollusca: 

Pelecypoda) of the North American Great 
Lakes. Amer. Midi. Nat., 67(1):194-198. 

HERRINGTON, H. В., 1950, Sphaeriidae of 
Athabaska and Great Slave Lakes in north- 
western Canada. Canadian Field- Naturalist, 
64(l):25-32. 

, 1962, A revision of the Sphaeriidae 

of North America (Mollusca: Pelecypoda). 
Misc. Publ. No. 118, Univ. Mich. Mus. Zool. 
p. 1-74, pis. 1-7. 

HOUGH, J. L., 1958, Geology of the Great 
Lakes. Univ. 111. Press, Urbana, 313 p. 

KEW, H. W., 1893, The dispersal of shells. 
Kegan Paul, Trench, and Trubner, London, 
291 p. 

MORRISON, J. P. E,, 1932, A report on the 
Mollusca of the Northeastern Wisconsin 
Lake District. Trans. Wise. Acad. Sei., 
27: 359-396. 

ODHNER, N. H., 1921, On some species of 
Pisidium in the Swedish State Museum. 
J. Conchol., 16(7):218-223. 

, 1951, The mountain fauna of the 

Virihaure Area in Swedish Lapland. Lunds 
Univ. Ârsskrift. N. F. Avd. 2, 46(2):26-50. 

ORTMANN, A. E., 1924, Distributional features 
of Naiades in the tributaries of Lake Erie. 
Amer. MidL Nat., 9(3):101-117. 

STERKI, v., 1895, Two new Pisidia, Nautilus, 
8(9):97-100. 

, 1916, A preliminary catalogue of 

the North American Sphaeriidae. Ann. Car- 
negie Mus., 10(3/4): 429-474. 

VAN DER SCHAUE, H., 1938, The Naiad fauna 
of the Huron River, In southeastern Michigan. 
Misc. Publ. No. 40, Univ. Mich. Mus. ZooL, 
83 p. 

, 1945, The value of mussel distribu- 
tion in tracing stream confluence. Pap. Mich. 
Acad. Sei., Arts and Lett., 30:355-373. 

WALKER, В., 1898, The distribution of the 
Unionidae in Michigan. Privately printed by 
the author, 23 p. 

, 1909, Annotated list of the Mollusca 

of Isle Royale, Michigan. In C.C.Adams: An 
ecological survey of Isle Royale, Lake Su- 
perior. Ann. ilep. Geol. Surv. Mich, for 1908, 
Wynkoop, Hallenbeck and Crawford, Lansing, 
p. 281-298. 

, 1913, The Unione fauna of the Great 



Lakes. Nautilus, 27(2-5):18-23, 29-34, 40- 
47, 56-59. 
WINS LOW, M. L., 1926, A revised check list of 
the Michigan Mollusca. Occ. Pap. No. 181, 
Univ. Mich. Mus, ZooL, 28 p. 



SPHAERIID DISTRIBUTION IN MICHIGAN 157 



ZUSAMMENFASSUNG 
DIE VERBREITUNG DER SPHAERIIDEN (PELECYPODA) IN MICHIGAN 

Ungefähr die Hälfte der 31 gegenwärtig im Staate Mchigan, in den Vereinigten 
Staaten von Amerika vorkommenden Arten von sphaeriiden Muscheln mit ihren 
"Formen" sind in diesem Staate allgemein verbreitet während die übrigen von 
geomorphologisch oder ökologisch beschränkter Verbreituлg sind. Während des 
Pleistozäns besiedelten vermutlich jene Spheriiden die sich im Mississippibecken 
befanden (ebenso wie die Unioniden Muscheln) die Gegend vom Süden her indem sie 
stromaufwärts in den post-glazialen Flüssen wanderten welche die ungeheuren Seen 
entwässerten die den Raum der heutigen Grossen Seen einnahmen. Die Hauptein- 
wanderungswege vom Mississipibecken her waren (1) für Michigans obere oder 
nördliche Halbinsel das Tal des Foxflusses im östlichen Wisconsin und (2) für die 
untere oder südliche Halbinsel der Illinois - Des Piaines Wasserweg welcher den 
glazialen Chicagosee (das heutige südliche Becken des Michigansees) entwässerte 
und der eiszeitliche Maumeefluss, welcher den damaligen Maumeesee (das Becken 
des jetzigen Eriesees) entleerte. Die darauffolgende Bildung der heutigen Seenkette 
mit ihren neuen Wasserscheiden und östlichem Abfluss unterbrach die vorherigen 
Konfluenzen und schuf ein diskontinuirliches Verbreitungsbild indem einige Arten 
isoliert wurden und der Ausbreitung anderer, zu verschiedenen Zeiten und mit 
minderem oder grösserem Erfolge, Grenzen gesetzt wurden. Ein schlagendes Bei- 
spiel für ein solches Hindernis stellt der eiszeitliche Grandfluus dar, welcher das 
Gebiet der unteren Halbinsel durchquerte. Nachdem der südliche Teil dieser 
Halbinsel von Sphaeriiden besiedelt worden war, versperrte dieser das weitere 
Vordringen dreier Arten: Pisidium cruciatum , P. punctiferum und Sphaerium 
trans versum nach dem Norden. Gleicherweise bildete er die südliche Grenze für 
P. insigne, eine Art welche nicht unmittelbar vom Süden sondern auf Umwegen vom 
Norden her in die Halbinsel eingedrungen war. Später teilte sich der Grandfluss in 
2 nach entgegengesetzte Seiten fliessende, den nach Osten verlaufenden heutigen 
Saginawfluss und den nach Westen strömenden heutigen Grandfluss, und zwar noch 
bevor P. cruciatum undP. punctiferum vomWestenher in den Saginaw eingedrungen 
waren. Das grösstenteils oder ausschliesslich auf die den Staat umgebenden Grossen 
Seen beschränkte Vorkommen vonP. conventus , P. idahoense und S. nitidum, welche 
Bewohner tiefer und kalter Gewässer sind, lässt sich auf ökologischer Grund- 
lage erklären; das gleichfalls auf die Grossen Seen sowie deren Abflussgebiet be- 
schränkte von P. henslowanum , P. amnicum und S. comeum durch die wahrschein- 
lich erst in der Gegenwart erfolgte Einschleppung aus Europa. Die unmittelbaren 
Ursachen für die örtliche Begrenzung verschiedener anderer Arten oder Formen 
1st jedoch weniger klar erkenntlich. 

Im allgemeinen lässt sich sagen, dass einerseits durch aktive Wanderung in 
Zeiten abwechselnder Überschwemmungen und niederer Wasserstände welche 
schliesslich die ehemaligen Zusammenhänge zerstörten und andrerseits durch 
Verschleppung, teils innerhalb der Wasserwege mittels anderer Wassertiere wie 
Krebse, Frösche oder Fische, teils Überlands durch Wasservögel, das ursprüngliche 
Verbreitungsbild vieler Sphaeriiden in den Binnengewässern Michigans verdunkelt 
wurde. Ein solches ist nur noch bei P. cruciatum , P. punctiferum und S. trans- 
versum klar erkenntlich während es bei P. /aZZax, P. insigne, P. obtusale, P. walkeri 
•\iíá S . fabale teilweise verschleiert ist. 



158 W. H. HEARD 



RESUME 
LA DISTRIBUTION DES SPHAERIIDES (PÉLÉCYPODES) AU MCHIGAN 

A peu près la moitié des 31 espèces de bivalves sphaeriides et de leurs 
"formes" habitant présentement l'état de Michigan aux États Unis d'Amérique y ont 
une distribution généralisée, tandis que la répartition du reste des espèces est 
géomorphologiquement ou écologiquement restreinte. Pendant l'époque pleistocene 
les sphaeriides présents dans le bassin du Mississippi ont vraisemblablement colonisé 
la région du Michigan de par le sud (tout comme les bivalves unionides) en re- 
montant le cours des rivières post-glaciales par lesquelles s' évidaient les immenses 
pièces d'eau occupant la région des grands lacs présents. Les routes principales 
d' immigration du bassin du Mississippi étaient: (1) pour la péninsule supérieure ou 
septentrionale, la vallée du Fox, dans le Wisconsin oriental et (2) pour la péninsule 
inférieure ou méridionale, la voie Illinois -Des Plaines, par laquelle s'effectuait le 
drainage du lac Chicago glacial (correspondant au bassin méridional du présent Lac 
Michigan) et le fleuve glacial Maumee par lequel s' écoulaient les eaux du lac Maumee 
glacial (le bassin du Lac Erie présent). La formation subséquente des Grands Lacs 
actuels, avec les nouvelles lignes de partage des eaux, et leur écoulement vers 
l'est, rompit les confluences antérieures et créa une distribution sphaeriide dis- 
continue, isolant certaines espèces et entravant plus ou moins efficacement en di- 
verses périodes le progrès de certaines autres. La rivière Grand glaciale.traversant 
la région de la péninsule inférieure, fournit un exemple frappant d'un tel obstacle: 
suivant la colonisation de l'extrême sud de cette péninsule par les sphaeriides, elle 
limita effectivement la diffusion vers le nord des espèces Pisidium cruciatum, P. 
punctiferum et Sphaeriwn trans ve rsum . De même, cette rivière constitua la limite 
sud pour le P. insigne qui tí a. pa.s pénétré dans la peninsula directement par les voies 
méridionales, mais l'a envahie du nord par des routes plus indirectes. La rupture 
du Grand glacial, donnant naissance à deux fleuves courant en sens opposé, le 
présent Saginaw prenant cours vers l'est et le présent Grand s'écoulant vers l'ouest, 
eut lieu avant que les espèces?, cruciatumet P. pune tifemtu eussent pu parvenir de 
1' ouest dans le bassin du Saginaw. La répartition, restreinte largement ou exclu- 
sivement aux Grands Lacs bordant l'état, de P. conventus, P. idahoense et S. nitidum, 
espèces d' eau froide et profonde, s' explique à base écologique; celle de P. hen- 
slowanum, P. amnicum et S. corneum , espèces d'origine européenne, qui sont 
localisées dans les Grands Lacs et leur ligne de drainage, par leur invasion pro- 
bablement récente. Les causes immédiates de la distribution limitée de certaines 
autres espèces sont moins apparentes. 

En général l'on peut dire que la distribution orginale de beaucoup de sphaeriides 
dans les bassins riverains du Michigan a été obscurcie d'une part par une migration 
active pendant les périodes alternantes d'inondations et de niveaux bas qui finalement 
rompirenet les confluences antérieures et, d'autre part, par un transport passif, 
soit à l'intérieur de ces mêmes voies d'eau au moyen d'autres animeaux aquatiques 
tels qu'écrevisses, grenouilles ou poissons, soit à travers la région par l'entremise 
d'oiseaux aquatiques. Le tracé de la distribution originale n'est encore clairement 
visible que pour les espèces?, cruciatum, P. punctiferum et S . transversum , tandis 
qu'il est partiellement masqué pour les espèces P.fallax, P. insigne, P. walkeri et 
S. /abale. 



SPHAERIID DISTRroUTION IN MICHIGAN 159 



RESEÑA 
LA DISTRIBUCIÓN DE SPHAERIIDAE (PELECYPODA) EN MICHIGAN, E.E.U.U. 

Como la mitad de las 31 especies y sus formas de esféridos que habitan hoy 
en Michigan son más о menos de distribución general en el estado, aunque el resto 
tienen un área geomorfológicamente y ecológicamente restricta. Durante el 
Pleistocene, estos esféridos presumiblemente repoblaron la región, desde el sur, 
por migración activa remontando las aguas a través de las confluencias de los 
cursos posglaciales. Las rutas mayores de migración desde el río Mississippi 
hacia el interior de Michigan fueron: (1) Hacia la Alta Península de Michigan, el 
Valle del Río Fox en Wisconsin oriental, y (2) Hacia la Baja Península el canal 
niinois--Des Plaines que drenaba el lago glacial Chicago (la cuenca sur del presente 
Lago Michigan) y el Rio glacial Maumee que drenaba el Lago Maumee (cuenca del 
presente Lago Erie). 

Después que la parte sur de la Baja Península de Michigan fué repoblada, su 
dispersión fué diversamente obstaculizada. El Rio Grande glacial limitó la dis- 
persión hacia el norte de Pisidium cruciatum, P. punctiferum , y Sphaeriuní trans- 
versum, y más tarde se dividió en el presente Rio Saginaw de curso oriental y el 
Rio Grande que corre hacia el oeste antes que P. cruciatum y P. punctiferum 
pudieran entrar en la corriente del Saginaw desde el oeste. La distribución, 
restricta mayormente a los Grandes Lagos fronterizos del estado, de P. conventus, 
P. iâahoense,, y s. nitidum, las cuales son especies de aguas profundas y frias, 
puede explicarse ecológicamente; lade P./îêwstowanMw, P. amnicum and S. comeum, 
que son restrictas a los Grandes Lagos y sus drenajes, puede explicarse por su 
reciente importación de Europa. Las causas inmediatas de las ocurrencias locales 
de muchas otras especies y formas, sin embargo son menos aparente. 

La migración activa durante periodos que alternaban entre inundaciones y aguas 
bajas, que terminó en la desuniónde las confluencias, el transporte pasivo mediante 
otros animales acuáticos como langostas de agua dulce, ranas y peces, y el trans- 
porte aereo por aves acuáticas, alteraron la distribución original de los esféridos 
en Michigan. El tipo original es todavía evidente en la distribución de P. cruciatum, 
P. punctiferum, y S. transversum, pero está parcialmente disimulado en P. fallax, 
P. insigne, P. obtusale,P. walkeri, y S. fabale. 



КОНСПЕКТ 
РАСПРОСТРАНЕНИЕ SPHAERIIDAE (BIVALVIA) В МИЧИГАНЕ, США. 

Василий X. Хэрд 

Около половины всех 31 вжда и форм двустворчатых моллюс- 
ков семейства Сфэриидэ, живущих в штате Мичиган, равномерно 
рассеяно по территории штата, в то время как остальная часть 
их резко разграничена геоморфологически и экологически. Во 
время плейстоценовой эпохи, виды ныне населяющие штат, веро- 
ятно, колонизировали его двигаясь с юга, как это делали пер- 
ловицы и беззубки, мигрируя на север вверх по течению после- 
ледниковых ручьев, которые питались из громадных водных скоп- 
лений теперешних Больших Озер. Главными путями миграции из 



160 W. H. HEARD 

бассейна p. Миссиссиппи были: 1 ) в верхние полуострова шта- 
та, в долину Фокс Ривэр в восточной части штата Висконсин и 
2) в нижние полуостроваштата, в канал Иллиной-Дэс Плэйнс, 
который питался из ледникового Озера Чикаго (южная база сов- 
ременного Озера Мичиган) и из ледниковой реки Мауми, вытекав- 
шей из озера того же названия (база современного озера Ири). 
Последовавшее формирование современных Больших Озер, с их 
новыми притоками и истоками на восток, прервало прежние сте- 
чения и создало оторванные разлития вод, изолируя виды мол- 
люсков и останавливая развитие других видов в разное время 
с различными результатами. Показательный пример такого пре- 
пятствия была ледниковая Гранд Ривэр, курс которой пересекал 
площадь Нижнего Полуострова; после того, как южная часть это- 
го полуострова была снова заселена семейством Сфериидэ, она 
остановила продвижение на север трех видов: Pisidium cniciatum, 
P. punctiferum и Sphaerium transversum. Таким образом эта 
река образовала южную границу для вида Р. insigne, который 
не проник на полуостров прямо с юга, но - с севера более слож- 
ными путями. Ледниковая река Гранд Ривэр позже разделилась на 
два рукава, текште в пропивоположных направлениях, река Са- 
гино сегодняшнего дня, текущая в восточном направлении и 
современная Гранд Ривэр, текщая на запад, прежде чем Р. сги- 
ciatunj, и Р. piinctiferiim могли проникнуть в Сагино с запада. 

Распространение ограниченное главным образом Большими 
Oзepa^ш по линии штатной границы для Р. conventum, Р. idahoense 
и S. nitidmn - видам более глубокой и холодной воды, можно 
на основании экологии. Распространение же видов Р. henslo- 
wanum, P. amniciim S. corneiim, видам ограниченным Больши- 
ми Озерами и их истоками, можно объяснить, вероятно, их не- 
давним появлением из Европы. Непосредственные причины огра- 
ничения ареала некоторых других видов или форм менее ясны. 

Вообще возможно, что активная мигращм в периоды пере- 
межающихся половодий и обмельчаний, которые в конечном ре- 
зультате разорвали прежнее слияние вод, также как и пассив- 
ное их перемещение, отчасти в этих водах другими пресновод- 
ными животными как раки, лягушки и рыбы, а отчасти водяными 
птицами, прежнее распространение семейства Сфэридэ во внут- 
ренних водах озера Мичиган. Структура прежнего распростра- 
нения все еще ясна только для видов Р, criiciatiwi, Р. puncti- 
ferum и S. transversum, в то время как она отчасти скрыта 
для видов Р. fallax, Р. insigne, Р. obtusale, Р. walkeri и 
S. f abale. 



DIRECTIONS TO AUTHORS 



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MALACOLOGIA is published at irregular intervals 
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MALACOLOGIA est publié a intervalles irréguliers 
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MALACOLOGIA wird vom Institute of Malacology, 
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servirán como editores, son: 



Журнал МАЛАКОЛОГИЯ издается нерегулярно 
Объединенным институтом малакологии, 2i(.15 South 
Circle Drive, Анн Арбор, Мичиган, США. Члены 
Института, являются также редакторами данного 
журнала--: 



D. W. TAYLOR, President 
U.S. Geological Survey 
U.S. National Museum 
Washington 25, D.C., U.S.A. 



M. R. CARRIKER, President-Elect 
Systematic s- Ecology Program 
Marine Biological Laboratory 
Woods Hole, Massachusetts, U.S.A. 



R. ROBERTSON, Vice President 
The Academy of Natural Sciences 

of Philadelphia 
Philadelfáiia 3, Pennsylvania, U.S.A. 



A. G. SMITH, Vice President 
Department of Invertebrate Zoology 
California Academy of Sciences 
San Francisco 18, California, U.S.A. 



J. B. BURCH, Secretary-Treasurer 
Museum of Zoology 
The University of Michigan 
Ann Arbor, Michigan, U.S.A. 



E. G. BERRY 

Laboratory of Parasitic Diseases 

National Institute of Allergy 

and Infectious Diseases 
National Institutes of Health 
Bethesda 14, Maryland, U.S.A. 



N. F. SOHL 
U.S. Geological Survey 
U.S. National Museum 
Washington 25, D.C, U.S.A. 



Vol. 1, No. 1 MALACOLOGIA October 1962 



CONTENTS 

Page 
MALACOLOGIA, An International Journal of Malacology 1 

D. W. TAYLOR and N. F. SOHL 

An outline of gastropod classification 7 

H. W. HARRY 

A critical catalogue of the nominal genera and species of 

neotropical Planorbidae 33 

J. B. BURCH 

Cytotaxonomic studies of freshwater limpets (Gastropoda: 

Basommatophora) I. The European Lake Limpet, 

Acroloxus lacustris 55 

I. STIGLINGH, J. A. VAN EEDEN and P. A. J. RYKE 

Contributions to the morphology of Bulinus tropicus * 
(Gastropoda: Basommatophora: Planorbidae) 73 

H. J. WALTER 

Punctation of the embryonic shell of Bulininae (Planorbidae) 
and some other Basommatophora and its possible taxonomic- 
/Ж- phylogenetic implications 115 

W. H. HEARD 

Distribution of Sphaeriidae (Pelecypoda) in Michigan, U.S.A 139 



VOL 1 NO. 2 



JULY 1963 









MALACOLOGIA 



International Journal of Malacology 



Revista Internacional de Malacologia 



Journal International de Malacologie 



Международный Журнал Малакологии 



Internationale Malakologische Zeitschrift 



MALACOLOGIA 



ANNE GISMANN, General Editor 
19, Road 12 
Maadi, Egypt 
U. A. R. 



B. BURCH, Managing Editor 
Museum of Zoology 
The University of Michigan 
Ann Arbor, Michigan, U. S. A. 



M. HUBER, Business Manager 
Museum of Zoology 
The University of Michigan 
Ann Arbor, Michigan, U, S. A. 



EDITORIAL BOARD 
SCHRIFTLEITUNGSRAT 



CONSEJO EDITORIAL 
CONSEIL DE RÉDACTION 



РЕДАКЦИОННАЯ КОЛЛЕГИЯ 



P. О, AGOCSY 

Magyar Nemzeti MÚzeum 
Természettudományi Múzeum 
Baross U, 13 
Budapest, VIII., Hungary 

К. H. BARNARD 

South African Museum 

Cape Town 

Republic of South Africa 

С R. BOETTGER 

Technischen Hochschule 

Braunschweig 
Braunschweig 
Pockelsstrasse 10a 
Germany 

A. H. CLARKE, JR. 

National Museum of Canada 
Ottawa, Ontario, Canada 

С J. DUNCAN 

Department of Zoology 
University of Liverpool 
Liverpool, England 

E. FISCHER-PIETTE 

Museum National d'Histoire 

naturelle 
55 rue de Buff on 
Paris V^, France 

A. FRANC 

Faculté des Sciences 
55 rue de Buff on 
Paris Ve, France 

K. HATAI 

Institute of Geology and 

Paleontology 
Tohoku University 
Sendai, Japan 



N. A. HOLME 

Marine Biological Association 

of the United Kingdom 
The Laboratory, Citadel Hill 
Plymouth, Devon, England 

G. P. KANAKOFF 

Los Angeles County Museum 
900 Exposition Boulevard 
Los Angeles 7, California 
U. S. A. 

A. M. KEEN 

Department of Geology 
Stanford University 
Stanford, California, U. S. A. 

Y. KONDO 

Bernice P. Bishop Museum 
Honolulu 17, Hawaii, U. S, A. 

N. MACAROVICI 

Laboratoire de Géologie 
Université "Al. I. Cuza" 
Ia§i, Romania 

D. F. McMICHAEL 

The Australian Museum 
College Street 
Sidney, Australia 

J. E. MORTON 

Department of Zoology 
The University of Auckland 
Auckland, New Zealand 

W. K, OCKELMANN 

Marine Biological Laboratory 
Gr(íínnehave, Helsingdr 
Danmark 



W. L. PARAENSE 

Centro Nacional de Pesquisas 

Malacológicas 
Caixa Postal, 2113 
Belo Horizonte 
Minas Gérais, Brasil 

J. J. PARODIZ 

Carnegie Museum 
Pittsburg 13, Pennsylvania 
и, S. A. 

R, D. PURCHON 

Dept. of Botany and Zoology 
Chelsea College of Science 

and Technology 
London, S. W. 3, England 

S. G. SEGERSTRÂLE 

Zoological Museum of 

Helsinki University 
P.-Rautatiekatu 13 
Helsinki, Finland 

J. STUARDO 

Departamento de Zoología 
Instituto Central de Biología 
Universidad de Concepción 
Cas. 301, Concepción, Chile 

W. S. S. VAN DER FEEN - VAN 
BENTHEM JUTTING 

Zoologisch Museum 

Amsterdam, The Netherlands 

С M. YONGE 

Department of Zoology 
The University 
Glasgow, Scotland 

A. ZILCH 

Senckenberge-Anlage 25 
6 Frankfürt am Main 1 
Germany 



MALACOLOGIA was established with the aid of a grant (NSF-G24250) from the National Science Foundation, 
Washington, D. C, U. S. A. 

MALACOLOGIA wurde unter Beihilfe einer Unterstützung (NSF-G24250) der National Science Foundation, 
Washington, D. C, U. S. A., gegründet. 

MALACOLOGIA fut établi avec l'aide d'une subvention (NSF-G24250) de la National Science Foundation, 
Washington, D. C, U. S. A. 

MALACOLOGIA fue establecida con la ayuda de una subvención (NSF-G24250) de la National Science 
Foundation, Washington, D, C, U. S. A. 

Журнал МАЛАКОЛОГИЯ был подготовлен к изданию при помощи субсидии (NSF - G24250) от Госу- 
дарственного научного общества в Вашингтоне, США. 



MALACOLOGIA is prepared in the Mollusk Division, Museum of Zoology, The Univerisity of Michigan and 
published at irregular intervals by the Institute of Malacology, 2415 South Circle Drive, Ann Arbor, Michigan, 
U. S. A. The Sponsor Members of this Institute, also serving as editors are: 

MALACOLOGIA wird in der "Mollusk Division, Museum of Zoology" der Universität von Michigan fertiggestellt 
und in unregelmässigen Zeiträumen vom "Institute of Malacology", 2415 South Circle Drive, Ann Arbor, Michigan, 
U. S. A. herausgegeben. Die gründenden Mitglieder dieses Institutes, die auch als Schriftleiter fungieren sind: 

MALACOLOGIA est élaboré au Département de Mollusque de Musée de Zoologie du l'Université de Michigan 
et publié à intervalles irréguliers par l'Institut de Malacologie, 2415 South Circle Drive, Ann Arbor, Michigan, 
и. S. А. Les membres du Comité de Patronage de cel Institut constituent en même temps le Comité de Publication 
de MALACOLOGIA. Ce sont: 

MALACOLOGIA se publicará a intervalos irregulares por el Institute of Malacology, Inc., 2415 South Circle 
Drive, Ann Arbor, Michigan, U. S. A. Los miembros adhérentes de este instituto, quienes también servirán como 
editores, son: 

Журнал МАЛАКОЛОГИЯ издается нерегулярно объединенным Институтом Малакологии, 2415 South Circle 



Drive, Ann Arbor, Michigan, U. S. A. 
редакторами данного журнала: 

D. W. TAYLOR, President 
U. S. Geological Survey 
U. S. National Museum 
Washington 25, D, C, U. S. A. 

A. G. SMITH, Vice-President 
Department of Invertebrate Zoology 
California Academy of Sciences 
San Francisco 18, California, U. S. A. 



Ответственные Члены - Основатели Института являются также 



М. R. CARRIKER, President-Elect 
Systematics-Ecology Program 
Marine Biological Laboratory 
Woods Hole, Massachusetts, U. S. A. 

E. G. BERRY, Vice-President 
Laboratory of Parasitic Diseases 
National Listitute of Allergy 

and Infectious Diseases 
National Institutes of Health 
Bethesda 14, Maryland, U. S. A. 



R. ROBERTSON, Vice-President 
The Academy of Natural 

Sciences of Philadelphia 
Philadelphia 3, Pennsylvania, 

U. S. A 
N. F. SOHL, Secretary 
U. S. Geological Survey 
U. S. National Museum 
Washington 25, D. C, U.S.A. 



J. B. BURCH, Treasurer 
Museum of Zoology 
The University of Michigan 
Ann Arbor, Michigan, U. S. A. 

Participating Members of the Institute of Malacology are: 

Aktiv teilnehmende Mitglieder des Malakologischen Institutes sind: 

Les membres actifs de l'Institut de Malacologie sont: 



P. 


0. AGÓCSY 


K. 


HATAI 


к. 


H. BARNARD 


N. 


A. HOLME 


с. 


R. BOETTGER 


G. 


P. KANAKOFF 


A. 


H. CLARKE, JR. 


A. 


M. KEEN 


С. 


J. DUNCAN 


Y. 


KONDO 


E. 


FISCHER - PIETTE 


N. 


MACAROVICI 


A. 


FRANC 


D. 


F. McMICHAEL 


A. 


G ISM ANN 


J. 


E. MORTON 






W, 


. K. OCKELMANN 



W. L. PARAENSE 

J. J. PARODIZ 

R. D.PURCHON 

S. G. SEGERSTRÂLE 

J. STUARDO 

W. S. S. VAN DER FEEN 

H. VAN DER SCHALIE 

С. M. YONGE 

A. ZILCH 



Members-at-Large of the Institute of Malacology include all subscribers to MALACOLOGIA. 
Alle Abonnenten von MALACOLOGIA gelten als ordentliche Mitglieder des Institutes. . 
Tous les abonnés de MALACOLOGIA sont Membres Associés de l'Institut de Malacologie. 



Subscription price for MALACOLOGIA is fS.OO (U. S. A.) or £. 1.16. or fr. 25. Subscription requests, payments 
and enquiries can be sent to any of the Editors listed below: 

Der Abonnementspreis für MALACOLOGb^ beträgt jährlich S5.00 (U. S. A) oder JC 1.16. oder französische 
fr. 25.00. Abonnementsbestellungen, Einzahlungen und Anfragen sind an einen der unten angegebenen Schrift- 
leiter zu richten: 

Le prix de l'abonnement à MALACOLOGIA est de 5 dollars ou 1.16 livres ou 25 francs (français). Les demandes 
d'abonnement, les paiements, et les demandes renseignements, peuvent être envoyés à l'un des membres de la 
liste suivante: 

Prof. E. FISCHER-PIETTE 



Dr. J. B. BURCH 

Museum of Zoology 

The University of Michigan 

Ann Arbor, Michigan, U. S. A. 



Dr. С J. DUNCAN 
Department of Zoology 
University of Liverpool 
Liverpool, England 



Muséum National d'Histoire 

naturelle 
55 rue de Buff on 
Paris ve, France 



Institute of Malacology 

Third Annual Meetir^ 

Washington, D. C, August 1963 

Notice of the Third Annual Meeting of the Sponsor Members of the Institute of 
Malacology is hereby published as provided by Article III, Section 1 of the Constitution 
of the Institute. Participating Members and Members-at-Large on record as of July 1, 
1963 may attend the meeting if they so desire, but such attendance is not necessary 
for proper handling of business matters. The meeting will be held sometime during 
the International Congress of Zoology in Washington, D. C, U. S. A., August 20-27, 1963. 
Notice of a specific time and place will be available at the Congress. 

Malakologisches Institut 

3. jährliche Sitzung 

Washington D. С, August 1963 

Gemäss Artikel III, Abschnitt I, der Verfassung des Malakologischen Instituts wird 
hiemit die 3. jährliche Zusammenkunft der gründenden Mitglieder des Instituts öffentlich 
bekanntgegeben. Aktive Mitglieder, sowie alle bis zum 1. Juli 1963 ordnungsgemäss 
eingetragenen ordentlichen Mitglieder, können, falls sie es wünschen, der Sitzung 
beiwohnen. Anteilnahme ist jedoch für den Ablauf der Geschäfte nicht erforderlich. 
Die Zusammenkunft findet in Washington D. C, währenddes Internationalen Zoologischen 
Kongresses vom 20.-27. August 1963 statt, bei welchem dann Näheres Über Ort und 
genauen Zeitpunkt in Erfahrung zu bringen ist. 

Institut de Malacologie 

Зете Session Annuelle 

Washington D. С, Août 1963 

Selon l'article Ш de la section I de la constitution de l'Institut de Malacologie, nous 
annonçons par la présente publication la 3^"^^ réunion annuelle du Comité de Patronage 
de l'Institut. Les membres actifs ainsi que les membres associés régulièrement 
inscrits en date du l^r Juillet 1963 peuvent, s'ils le désirent, assister à la session, 
mais leur présence n'est point nécessaire pour le déroulement des affaires. La 
réunion aura lieu à Washington D. C, à l'occasion du Congrès International de Zoologie 
allant du 20 au 27 Août 1963, pendant lequel des renseignements plus précis quant au 
lieu et à l'heure de la réunion pourront être obtenus. 

Instituto de Malacologia 

Tercer Mitin Anual 

Washington, D. С, Agosto 1963 

Convócase, de acuerdo con las provisiones del Artículo III, sección la de los Estatutos 
del Instituto, al Tercer Mitin Anual de los Miembros Patrocinadores. Miembros regu- 
lares y Adhérentes, registrados hasta el IQ de Julio, 1963, pueden concurrir al mitin 
si asi lo desean, pero tal asistencia no es imprescindible para el manejo de cuestiones 
administrativas y financieras. El mitin tendrá lugar en momento oportuno, durante 
el Congreso Internacional de Zoología en Washington, D. C, Agosto 20-27, 1963. Fecha, 
hora y lugar se notificará en ese Congreso, 



МАЛАКОЛОГИЯ, международный журнал малакологии 



Основатели журнала МАЛАКОЛОГИЯ 
надеются, что этот журнал заполнит 
ощутительный пробел в разных стра- 
нах, где работникам трудно было по- 
мещать длинные статьи или моногра- 
фии. Они также хотят создать меж - 
дународный дружеский обмен между 
малакологами разных стран. В США 
давно наблюдалась потребность в 
журнале, который был бы посвящен 
изучению всех областей малакологии 
и смог бы быстро печатать моногра- 
фии и более длинные труды. Неболь- 
шая группа малакологов, во время 
съезда Американского Союза Малако- 
логов, в Июне, 1961 г., обсудила 
возможность создания такого между- 
народного журнала. Им казалось, 
что такой журнал, не только даст 
возможность многим авторам печатать 
свои труды, но также и будет спо- 
собствовать быстрому распростране- 
нию и обменуидеями и сведениями 
между странами, если создать мно - 
гоязычный журнал с абстрактами. 

Казалось целесообразным испробо- 
вать долю возможной поддержки для 
такого журнала. Поэтому был разос- 
лан опросный лист 192 малакологам 
и зоологам, изучавшим моллюсков в 
разных странах. Группа, получившая 
такие анкеты, включала всех извест- 
ных нам малакологов во всем мире; 
имена их были взяты из списков чле- 
нов разных зоологических обществ, 
изследователей, чьи работы встреча- 
ются в печати, а также лиц, актив- 
ных в научных учреждениях. 

В результате 80^ опросных листов 
были возвращены; 92^ из них сочув- 
ственно откликнулись на создание 
такого органа печати, многие из них 
с энтузиазмом; 6^ осталось нейтраль 
ными, наконец, ?.% ответов были про- 
тив создания такого журнала. Многие 
корреспонденты не ограничились толь 
ко одним заполнением опросного блан 
ка, но и послали ряд ценных советов 
На основании такого количества воз- 



можных подписчиков, был базирован 
практически оплачиваемый журнал. 

Средства для основания МАЛАКОЛОГИИ 
и для содержания ее в течении пер - 
вых лет существования, были получе- 
ны из ссуды, данной для этой цели 
Национальным Научным Фондом, в Ва- 
шингтоне, Д. К. Такие ссуды даются 
только проверенным бесприбыльным 
организациям; таким образом, был ос- 
нован Институт Малакологии, отвеча- 
ющий всем требованиям закона. Группа 
основателей Института Малакологии 
является ответственной за выбор ре- 
дакторов и за все дальнейшее руко - 
водство журналом МАЛАКОЛОГИЯ. Тепе- 
решние члены Института Малакологии 
перечислены на первой странице нас- 
тоящего выпуска. 

Задачи цели МАЛАКОЛОГИИ могут быть 
суммированы следующим образом: 

1. Быстро печатать работы, кои слиш- 
ком длинны для большинства существу- 
ющих малакологических изданий. 

2. Держать на высоте научный уровень 
и непрерывность издания, также как 

и редактирование его. Состав Редак- 
ционной Коллегии будет увеличен дос- 
таточным числом редакторов, чтобы 
обеспечить охват главных областей 
малакологии во всех странах. Чтобы 
быть уверенными в оригинальности и 
технической компетенции изысканий, 
каждая рукопись будет рассматривать- 
ся двумя или более редакторами. 
3. Собрать в одном издании работы, 
которые иначе были бы разбросаны по 
различным научным изданиям, в надеж- 
деускорить плодотворный обмен сведе- 
ниями и идеями в области малакологии. 
4. Содействовать развитию сотрудни- 
чества и возбуждать интерес к мала- 
кологическим исследованиям, посред- 
ством международного журнала. 

Эльмер Г. Бэрри Робэрт Робэртсон 
Иван Б. Бёрч Двайт В. Тэйлор 
Мэльбурн Р.Каррикер Аллин Г. Смит 
Анна Гисман Норман Ф. Сол 



(161) 



SOME ASSOCIATIONS OF MARINE MOLLUSICS AND ALGAE IN PUERTO RICO ^ 

Germaine L, Warmke and Luis R. Almodovar ^ 

ABSTRACT 



During a study of marine moUusks associated with algae at La Parguera, Puerto Rico, 
some 90 mollusk species were found living on 25 common species of algae. A total of 
30,859 mollusks were obtained from 155 lots of algae in littoral zone ana coral reef 
areas. Of those mollusks 99% were tiny gastropods, about 3/4% were pelecypods, and 
about 1/4% Amphineura. Fifteen species of gastropods formed 94% of all mollusks col- 
lected. Red algae appear to be the favored habitat, averaging 296 mollusks per lot. 
Green algae ranked second, with 120 mollusks per lot. Brown algae yielded only 46 
mollusks per lot collected. 

Though most species of mollusks were collected on all groups of algae, in many cases 
the animals showed a preference for one group. A few species showed a striking prefer- 
ence for a specific alga, the best example being the association of Oxynoe antillarum with 
the alga Caulerpa racemosa. 

Numerous as these small mollusks proved to be on algae, the study brought to light 
10 species not previously reported from Puerto Rico. These are as follows: Amphi- 
thalamus vallei, Cyclostremiscus omatus, Marginellopsis serrei, Assiminea succinea, 
CoTidylo cardia smithii, Cyclostremiscus pulchellus, Cylindrobulla beauii, Peristichia 
agria,a.nd 2 unnamed species of Omalogyra. 



INTRODUCTION 

Numerous small marine mollusks live 
on algae. Almost a century ago Bergh 
(1871) listed and described several species 
living onalgaeof theSargassumSea. Cole- 
man (1940) and Wieser (1952) supplied 
valuable information on the fauna (in- 
cluding mollusks) living on marine algae 
in the Plymouth region of England. More 
recently Robertson (1960) pointed out that 
algae on mangrove roots in the Bahama 
Islands are thefavoredhabitatof many mi- 
nute mollusks. To our knowledge, detailed 
studies of association between mollusks 
and algae — particularly whether mollusks 
show preference for certain species of 
algae, or if they live on algae indiscrimi- 



nately — have not been made in the Carib- 
bean area. 

While looking over various col- 
lections of reef and bay algae in Puerto 
Rico, we found many marine mollusks, and 
this led to the present study of moUuscan- 
algal associations. The purpose of this 
study was to identify and determine the 
relative abundance of mollusks living on 
common red, green, and brown algae at 
La Parguera off the Southwest coast of 
Puerto Rico (see map of collecting area). 

METHOD OF COLLECTING 

All algae were collected from clear 
water, in depths of 1 to 10 feet, from bays 
and coral reef areas. The salinity in the 



^This research was aided in part by National Science Foundation Grant 14020 awarded 
to the junior author. 

2 Curator of Mollusks and Algologist, respectively, Institute of Marine Biology, Univ- 
ersity of Puerto Rico, Mayaguez, Puerto Rico. 



(163) 



164 



WARMKE AND ALMODOVAR 




-18°i 



Magueyes ^^';::=> 



PUERTO RICO 



Bahia Fosforescente 

Bahia Montai va 



Enri que ^ ^^^ata 



Magimo 




<^ 



Cristobal 



Laurel 



îrooai /-) /-, 



(porral 



Media Luna *^^^Z!!^ 

Turrumote I 



CARIBBEAN SEA 



lin ni 



05 




FIG. 1. Map of collecting area, south coast of Puerto Rico. 



collecting areas ranged between 34 and 36 
p. p.m. and the temperature from 27-32 C. 
To avoid contamination, each species of 
alga was collected separately by the junior 
author who used a face mask and snorkle. 
Only the part above the holdfast was col- 
lected, thus eliminating any shells that 
might have been in the substrate at the base 
of the plants. Each algal lot, which con- 
sisted of approximately 1 pound wet weight, 
was put into a plastic bucket and covered 
with 40% formalin. After 10 to 15 minutes 
in the solution, the alga was agitated to 
remove shells still clinging to the plants. 
The alga and liquid were removed, and the 
residue was dried and examined under a 
binocular dissecting microscope. Only 



mollusks that were alive at the time of col- 
lecting were recorded; obviously empty 
shells with hermit crabs are not included 
in the report. With the exception of four 
lots, all collections were made during the 
months of January and February 1959 and 
October and November 1960. 

FINDINGS 

Distribution of all Mollusks on Algae 

In the present study 30,859 mollusks^ 
were found living on 25 different species 
of algae. Of these, 30,529, or almost 99%, 
belonged to the class Gastropoda. Only 
258 Pelecypoda and 72 Amphineura were 



SThese specimens will be divided and placed in the following Institutions: The Institute 
of Marine Biology, Mayaguez, Puerto Rico; the Academy of Natural Sciences of Phila- 
delphia; the Museum of Comparative Zoology at Harvard College; and the U.S. National 
Museum in Washington, D.C. 



ASSOCIATIONS OF MARINE MOLLUSKS AND ALGAE 



165 



collected (Table 1). 

The red algae harbored many more 
mollusks than either the green or brown 
(Table 1). A total of 23,706 mollusks were 
collected from 80 lots of red algae, aver- 
aging 296 specimens per lot. On the green 
algae, 5,997 mollusks were collected from 
50 lots, or an average of 120 specimens 
per lot. The 25 lots of brown algae yielded 
a total of 1,156 mollusks, or 46 per lot. 

Distribution of Gastropods on the Three 
Groups of Algae 

The 15 most common species of 
gastropods found living on algae, arranged 
in decending order of abundance, are shown 
in Table 2. These 15 species, with a total 
of 29,277 specimens, represent 94% of the 
total number of mollusks collected during 
this study. 

Table 2 also shows the distribution 
of these gastropods on the red, green, and 
brown algae. Although most species were 
collected on all groups of algae, in many 
cases the animals showed preference for 
one group. The following species show 
preference for the red algae: Amphi- 
thalamus vallei Aguayo and Jaume, Bittum 
varium Pfeiffer, Columbella mercatoria 
Linné, Assiminea succinea Pfeiffer, and 
Rissoella caribaea Rehder. It should be 
noted that 79 to 92% of the specimens of 
each of these species were found on red 
algae. 

The gastropods showing preference 
for the green algae were: Oxynoe antilla- 
rum Mörch, Anachis pulchella Sowerby, 
Cyclostremiscus omatus Olsson and 
McGinty, Caecum pul с he Hum Stimp son, and 
Schismope cingulata O. G. Costa. Between 
58 and 98% of the specimens of each of 
these species were collected on green 
algae. The only gastropod preferring 
brown algae was Caecum (J\âeioceras) 
nitidum Stimpson, with 66% of its speci- 
mens on the brown algae. 

Most of the mollusks found living on 
algae are minute gastropods. Ihe 11 
most abundant species all are under 5 mm 
in length as adults, and the majority are 
2 mm or less. Abundant as these mol- 



lusks are, few are ever found by the 
average collector, and little is known about 
their habits. Of the ten most abundant 
gastropods collected from algae in the 
present study, four have not previously 
been reported from Puerto Rico (see 
Table 2). 

Amphithalamus vallei was by far the 
most common mollusk found living on algae 
during this study. Almost one -half of the 
total number of specimens collected were 
this species. Surprisingly enough it had 
not previously been reported from Puerto 
Rico. It was more than twice as common 
as the next most abundant species, Bitt- 
ium varium. Robertson (1960) found A. 
vallei to be the most abundant species in 
the red algae on mangrove roots in the 
Bahamas. 

Distribution of Gastropods on Red Algae 

Table 3 shows the distribution of 31 
species of gastropods on 12 species of red 
algae. The minute rissoid, Amphithalamus 
vallei, was the most abundant gastropod 
collected on red algae. It averaged almost 
156 specimens per lot on the 80 lots 
studied. This is twice as common as 
Bittium varium, which averaged 68 shells 
per lot. Bittium shows a striking prefer- 
ence for Laurencia obtusa; 2,859, almost 
one-half of the total specimens of this 
species were found on that alga. Another 
species with a preference for a specific 
alga is Assiminea succinea. A total of 
352 specimens of this species were col- 
lected, and of these, 283or 80%, were found 
on red algae. Most of these (269) were 
found on one lot of Amphiroa fragilissimxi 
collected in the bay area. All 41 specimens 
of Cerithium variabile С В. Adams were 
found on the single red alga, Centroceras 
clavulatum. However, this species is more 
often found under rocks or in Thalassia 
beds. 

A total of 2,401 Rissoella caribaea 
were collected (Table 2); of these 1,905, 
or about 79%, were found on red algae, 
Laurencia papulosa was host to a little 
over one-half (1,054) of the ÄzssoeZZa found 
on red algae. 



166 



WARMKE AND ALMODOVAR 



In addition to the 31 species of gastro- 
pods listed in Table 3, there were numer- 
ous others which appeared less commonly 
or only as juvenile forms; these are in- 
cluded under the miscellaneous column at 
the end of the table. The miscellaneous 
gastropods, listed in alphabetic order, are 
as follows: Acmaea (young), Alaba incerta 
Orbigny, Anachis (young), Л s ira ea (young), 
Atys riiseanaM.<5rch,Atys{young), Caecum 
coronellus Dall, Cerithium algicola C. B. 
Adams, Crassispira juscescens Reeve, 
Crepidula (young), Emarginula (young), 
Epitonium (young), Euchelus guttarosea 
Dall, Eulima sp., Fissurella (young), 
Haminoea (young), Hyalina sp., Marginella 
láctea Kiener, Modulus modulus Linne, 
Nitidella laevigata hinne, {young), Nitidella 
ocellata Gmelin, Odostomia.canaliculata С . 
В. Adams, Odostomia laevigata Orbigny, 
Oxynoe antillarum Mörch, Pedipes mir- 
abilis MQhlfeld, Peris tichia agria Dall, 
Persicula pulcherrimxi Gaskoin, Planaxis 
(young), Pseudostomatella coccinea A. 
Adams, Pus¿a /гап/еуг Dohrn, Pyrgocythara 
sp., Pyramidella sp., Seila adamsi H. C. 
Lea, Stomatella picta Orbigny, Tegula 
fasciata Born, Tricolia adamsi Phillippi, 
Tricolia bella M. Smith, Tricolia thalass- 
icola Robertson, Triphora sp.. Trivia 
leucospkaera Schilder, (young), Trun- 
catella sp., (young), Turridal (young), 
Triptychus niveus Mörch, Vitrinella 
(young). 

Of the 23,518 gastropods found on red 
algae, only 174, or less than 1% are listed 
in the miscellaneous column. Although the 
total number of specimens included in this 
group was small, it represents some 44 
different species (many incompletely 
identified). These 44, plus the 31 species 
included in Table 3, make a total of about 
75 species of gastropods found living on 
red algae. 

Distribution of Gastropods on the Green 
Algae . 

Table 4 shows the distribution of the 
31 most common gastropods on 10 species 
of green algae. A total of 5,926 specimens 
were found on the green algae; of these 



1,506, or almost one-fourth of the 
specimens, were Schismope cingulata. 
This minute (1 mm) snail averaged 
127 shells per lot on Cladophoropsis 
membranácea. Amphithalamus vallei, the 
second most abundant species on the green 
algae, also shows a striking preference for 
C. mem,branacea. Four -fifths of all A. 
vallei from green algae (815 of 1,026) were 
on this alga. 

Anachis pulchella Sowerby shows a 
preference for the Halimeda Silga.e. A total 
of 185 specimens of this species were col- 
lected; of these 133, or almost 72%, (Table 
2) were on the green algae. Table 4 shows 
that 109 of the 133 specimens on green 
algae were found on Halimeda (96 on 
Halimeda opuntia and 13 on Halimeda 
tridens). Most of the shells of this species 
were young; of the 185 total, only 18 were 
adults. This could indicate either that 
Anachis pulchella spends only the early 
stage of its life on algae, or that the col- 
lections were made during the early part 
of the breeding season. 

An excellent example of a gastropod 
showing algal specificity is Oxynoe 
antillarum. A total of 329 specimens 
were collected; of these 324, or ap- 
proximately 98.5% (lable 2) were found 
on the green algae. Further examination 
(Table 4) shows that 322 specimens re- 
covered on green algae were on Caulerpa 
(294 on Caulerpa racemosa and 28 on 
Caulerpa serhdarioides). The shells 
ranged in length from less than 1mm for 
young specimens, up to 5nim for adults. 
This would indicate that O. antillarum 
spends most of its life on Caulerpa, pre- 
ferring the species С racemosa. The 
yellow-green color of the live animal 
serves as an excellent camouflage on 
Caulerpa. This is in accord with findings 
of Gonor (1961), Keen and Smith (1961), 
and others indicating that Sacoglossans 
often are found in association with 
Caulerpa. 

In addition to the gastropod species 
listed in Table 4, there were numerous 
others which appeared less commonly or 
only as juvenile forms; these are included 
under the miscellaneous column. These, 



ASSOCIATIONS OF MARINE MOLLUSKS AND ALGAE 



167 



listed in alphabetical order, are as follows: 
Acmaea (young), Anachis (young), Bullata 
ovuliformis Orbigny, Cerithiopsis sp., 
Crassispira (young), Crepidula (young), 
Eulima sp., Fissurella (young), Hipponix 
(young), Hyalina {young) , Lobiger souverbii 
Fischer, Marginella láctea Kiener, 
Modulus (young), Nitidella (young), Peri- 
stichia agria, Per si aula pulcherrima 
Gaskoin, Pedipes mirabilis MOhlfeld, 
Planaxis lineatus da Costa, Pusza (young), 
Vitrinella (young). 

Only 111, or less than 2% of the 
5,926 gastropods found on green algae, are 
listed in the miscellaneous column. Al- 
though this group is small, it includes some 
20 different species (most of them too 
young to be identified). These 20, plus the 
31 species included in table 4, make a 
total of approximately 51 species of 
gastropods found living on green algae. 

Distribution of Gastropods on Brown Algae 

Table 5 shows the distribution of the 
31 most common gastropods on three 
species of brown algae. Caecum {Meio- 
ceras) nitidum was the most abundant 
gastropod on brown algae. This small, 
pale -brown Caecum shows a strong 
preference for Dictyota bartayresii. 
Of the 254 specimens of this species found 
on brown algae 245, or 95%,were recovered 
from D. bartayresii. 

Another gastropod showing specificity 
is Marginellopsis serrei; all 63 specimens 
of this species were found on Dictyota 
divaricata. However, on the red algae, 
where 70% of the Marginellopsis were 
found, it was less specific. Л Zuanza auberi- 
ana, when found on brown algae, also pre- 
ferred D. divaricata. 

Miscellaneous gastropods, which ap- 
peared less commonly or only as juvenile 
forms are shown at the bottom of Table 5. 
These, listed in alphabetical order, are 
as follows: Acmaea {young), Alaba incerta, 
Astraea (young), Cerithium algicola, 
Crepidula (young), Epitonium (young), 
Fissurella (young), Haminoea (young), 
Liotia (young), Marginella (young), Odost- 
omia canaliculata C.B, Ada.nis, Par vi tur bo 



sp., Planaxis lineatus, Tricolia adam,si, 
Vitrinella (young). 

Only 30 specimens were included 
under the miscellaneous heading, but these 
add 15 more species to the 31 listed on 
Table 5, making a total of some 46 species 
of gastropods found living on brown algae. 

Distribution of Pelecypods on Algae 

The distribution of pelecypods found 
living on species of red, green, and brown 
algae is presented in Table 6, 7, and 8. 
Only 258 specimens, or less than l%of the 
total mollusks collected were pelecypods. 

These pelecypods are listed below in 
order of relative abundance (the number of 
specimens follows each species). 

Brachidontes exustus Linné (182) 

Condylocardia smithii Dall (13) 

Musculus lateralis Say (13) 

Chione cancellata Linné, (young) (7) 
Area imbricata Bruguiére, (young) (4) 

Area zebra Swainson, (young) (2) 
Barbatia cancellaria Lamarck, 

(young) (2) 

Diplodonta sp., (young) (2) 

Anadara notabilis Röding, (young) (1) 

Codakia sp., (young) (1) 

Gouldia cerina С. В. Adams (1) 

Lima sp., (young) (1) 

Miscellaneous young pelecypods (29) 

Total number of 258 

In all, nine pelecypod species were 
identified; three others could be identified 
to genus only. Brachidontes exustus was 
the only reasonably common species; 182 
or 70% of all the pelecypods found on algae 
were this species. With the exception of 
Condylocardia smithii , Musculus lateralis, 
and Gouldia cerina all other species of 
pelecypods found were young. Conceivably 
some of the bivalves that are attached by 
a by ssus were not dislodged by the formalin 
treatment. 

Among the pelecypods, one species, 
Concylocardia smithii proved to be a new 
record for Puerto Rico. 



168 



WARMKE AND ALMODOVAR 



Distribution of Amphineura 

A total of 72 chitons were found on 
algae. This is less than 1/4% of the total 
specimens of mollusks collected. The 
distribution of the chitons on the species 
of algae is given in Tables 6, 7, and 8. 
The chitons are all less than 3 mm in length 
and probably are juvenile forms. Most of 
these appear to be young Ischnochiton 
papillosus C. B. Adams. 

The following species of algae aver- 
aged about 1 chiton per lot: the red alga 
Spyridia filamentosa (7 chitons on 5 lots of 
algae); the green zlgdiCauler pa eras sifolia 
(2 chitons on 2 lots), a.ndHalimeda opuntia 
(16 chitons on 13 lots); the brown alga 
Dictyota bartayresii (17 chitons on 19 lots). 

Importance of Red, Green, and Brown Algal 
Species as Mollusk Habitats . 

Twenty-five species of algae are 
listed in Tables 9 and 10 in order of rela- 
tive importance as habitats for mollusks. 
Eight of the 12 species of red algae aver- 
aged over 100 mollusks per lot (Table 9). 
The filamentous red alga, Coelothrix, 
grows in tangled cushions over rocks and 
dead corals. Its wiry texture and growth 
habit doubtless are of importance in giving 
shelter to such large populations of mol- 
lusks. Centroceras, Acanthophora, Laur- 
encia, Amphiroa, Ceramium, and Hypnea 
also have compact growth habits which 
provide suitable habitats for mollusks. 

Of the green algae, three species 
averaged over 100 mollusks per lot (Table 
10). Cladophoropsis membranácea is a 
common shallow -water alga that forms an 
extensive mat up to 6 inches in thickness. 
This mat provides ample space for abun- 
dant moUuscan populations. Halimeda 
opuntia and Caulerpa racemosa possess a 
series of branches that are entangled and 
also provide shelter and food for many 
mollusks. 



The brown algae are not common on 
reefs. The two genera studied were se- 
lected because of the abundant surface area 
they provide. Dîciyoto forms a thick carpet 
over sandy bottoms and mollusks live 
among its protective branches. 



ACKNOWLEDGMENTS 
Gratitude is expressed to Dr. Robert 
Robertson, of the Academy of Natural 
Sciences of Philadelphia, for his great help 
in the identification of many of the more 
difficult moUuscan species and for re- 
viewing the manuscript. For help in col- 
lection of live algae, special thanks are 
due to Mr. Victor Rosado of the Institute 
of Marine Biology. 



LITERATURE CITED 

BERGH, RUDOLF, 1871, Beiträge zur 
Kenntniss der Mollusken desSargasso- 
meeres. Verh. K. K. Zool.-Bot. Ges. 
Wien, Vol. 21: 1-36. 

COLMAN, JOHN, 1940, On the faunas in- 
habiting intertidal seaweeds. J. Marine 
Biol. Assoc. Vol. 24: 129-183. 

GONOR, J. J., 1961, Observations on the 
biology oí Lobiger serradifalci,a. shelled 
sacoglossan opisthobranch from the 
Mediterranean. Vie et Milieu, 12(3): 
381-403, 5 figs. 

KEEN, MYRA and SMITH, ALLYN, 1961, 
West American species of the bivalved 
gastropod genus Berthelinia. Proc. 
Calif. Acad. Sei., 30: (2): 47-66. 

ROBERTSON, ROBERT, 1960, The mol- 
lusk fauna of Bahamian mangroves [ab- 
stract] Amer. Malac. Union Ann. Repts., 
1959, 22-23. 

WIESER, W., 1952, Investigations on the 
microfauna of seaweeds inhabiting 
rocky coasts. J. Marine Biol. Ass., 
31: 145-174. 



ASSOCIATIONS OF MARINE MOLLUSKS AND ALGAE 169 



TABLE 1, Distribution of MoUusks by Classes on Red, Green, and Brown Algae 





CLASSES OF MOLLUSKS 




















GROUPS OF 
ALGAE 


GASTROPODA 


PELECYPODA 


AMPHINEURA 








Total No. 


Average 


Total No. Average 


Total No. 


Average 


Total No. 


Average 




specimens 
collected 


No. per 
lot 


specimens No. per 
collected lot 


specimens 
collected 


No. per 
lot 


specimens 
collected 


No. per 
lot 


RED 
(80 lots) 


23,518 


294.0 


156 2.0 


32 


0.4 


23,706 


296 


GREEN 
(50 lots) 


5,926 


118.5 


51 1.0 


20 


0.4 


5,997 


120 


BROWN 
(25 lots) 


1,085 


43.4 


51 2.0 


20 


0.8 


1,156 


46 


TOTAL 
on all algae 


30,529 


197.0 


258 1.7 


72 


0.5 


30,859 


199 



TABLE 2. Distribution of 15 Most Abundant Gastropod Species on Three Groups of Algae 





On Red Algae4 


On Green Algae^ 


On Brown Algae^ 




Gastropod Species 


Total Gastropods 
collected 


Total Gastropods 
collected 


Total Gastropods 
collected 


Total No. Gastropods 
on all Algae 




No. % 


No. % 


No. % 




Amphithalamus vdllei* 


12,465 92.4 


1,026 7.6 


3 .02 


13,494 


Bittium varium 


5,466 89.1 


494 8.1 


176 2.9 


6,136 


Schismope cingulata 


983 38.2 


1,506 58.4 


88 3.4 


2,577 


Rissoella caribaea 


1,905 79.3 


452 18.8 


44 1.8 


2,401 


Cyclostremiscus ornatus 


520 37.5 


843 60.8 


24 1.7 


1,387 


Marginellopsis serrei* 


381 69.9 


101 18.5 


63 11.6 


545 


Caecum pulchellum 


173 33.0 


307 58.5 


45 8.6 


525 


Albania auberiana 


258 51.1 


151 29.9 


96 19.0 


505 


Caecum nitidum 


112 29.2 


18 4.7 


254 66.2 


384 


Assiminea succinea* 


283 80.4 


63 17.9 


6 1.7 


352 


Oxynoe antillarum 


5 1.5 


324 98.6 




329 


Columbella mercatoria 


157 80.5 


34 17.4 


4 2.1 


195 


Anachis pulchella 


52 28.1 


133 71.9 




185 


Persicula lavalleeana 


81 44.3 


23 12.6 


79 43.2 


183 


Cerithium litteratum 


51 64.5 


19 24.5 


9 11.0 


79 



4 80 lots; ^ 50 lots; 6 25 lots. 

♦Species not previously reported from Puerto Rico. 



170 



WARMKE AND ALMODOVAR 





Average 

per lot 

on all 

red algae 

(80 lots) 


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(siOT TT) 

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(s;oT z) 
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(sioT 6) 
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(sîOT S) 

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<; от 


Amphithalamus vallei 
Bittium varium 
Rissoella caribaea 
Schismope cingulata 
Cyclostremiscus omatus 
Marginellopsis serrei 
Assim.inea succinea 
Alvania auberiana 
Caecum pulchellum 
Columbella mercatoria 
Caecum nitidum 
Persicula lavalleeana 
Arene tricarinata 
Anachis pulchella 
Cerithium letteratum 
Bulla striata 
Litiopa melanostoma 
Cerithium variabile 
Turbonilla abrupta 
Cerithium ebumeum 
Omalogyra sp. 1 
Búllala ovuliformis 
Tricolia tessellata 
Rissoina bryerea 
Cingulina babylonia 
Omalogyra sp. 2 
Parviturboides sp. 
Caecum floridanum 
Turbonilla sp. 
Anachis magelioides 
Clyclostremiscus pulchellus 
Miscellaneous 



Л ьр 



■3 ьс 



ASSOCIATIONS OF MARINE MOLLUSKS AND ALGAE 171 



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^ S ^ '^ 



J- u) 



^-2 



p i^ 



о 5 5 



I s -2 



о Ü <i » 



ë 2 s 






<» u) a <s) о 



a -^ 



и b. u, 



Se g 

a: о о 






172 



WARMKE AND ALMODOVAR 



TABLE 5. Distribution oí Gastropods on 3 Species of Brown Algae^^ 





SPECIES OF BROWN ALGAE 












Average per lot 










GASTROPOD SPECIES^2 


Dtctyotu 


Dictyota 


Padina 


on all brown algae 




bartayresii 


divaricata 


gymnospora 


(25 lots) 




(19 lots) 


(3 lots) 


(3 lots) 




Caecum i^eioceras) nitidum 


12.0 


1.0 


2.0 


10.16 


Bittium varium 


7.6 


7.7 


2.7 


7.04 


Albania auberiana 


2.6 


14.3 


1.0 


3.84 


Schismope cingulata 


3.1 


9,7 


- 


3.52 


Persicula lavalleeana 


3.9 


1.7 


- 


3.16 


Marginellopsis serrei 


- 


21.0 


- 


2.52 


Caecum pulchellum 


2.1 


1.7 


- 


1.80 


Rissoella caribaea 


1.6 


4.3 


- 


1.76 


Cerithium litteratum 


2.0 


- 


0.3 


1.52 


Cerithium ebumeum 


1.3 


2.3 


- 


1.24 


Bulla striata 


1.1 


0.7 


0.7 


0.96 


Cyclostremiscus omatus 


1.3 


- 


- 


0.96 


Arene tricarinata 


0.4 


1.7 


- 


0.52 


Modulus modulus 


0.4 


_ 


- 


0.32 


Turbonilla abrupta 


0.4 


- 


- 


0.32 


Tricolia tessellata 


0.2 


- 


- 


0.28 


Assiminea succinea 


0.2 


1.0 


- 


0.24 


Bullata ovuliformis 


0.3 


- 


- 


0.24 


Tegula fasciata 


0.2 


1.0 


- 


0.24 


Epitonium echinaticostum 


0.2 


0.3 


- 


0.20 


Pseudostomxitella coccínea 


0.2 


0.3 


- 


0.20 


Columbella mercatoria 


0.2 


- 


0.3 


0.16 


Rissoina bryerea 


0.1 


0.7 


- 


0.16 


Amphithalamus vallei 


- 


1.0 


- 


0.12 


Omalogyra sp. 1 


0.1 


0.7 


- 


0.12 


Nitidella nitida 


0.1 


0.3 


- 


0.08 


Odostomia laevigata 


0.1 


- 


- 


0.08 


Seila adamsii 


0.1 


- 


. 


0.08 


Tricolia bella 


0.1 


- 


- 


0.08 


Tricolia thalassicola 


0.1 


- 


. 


0.08 


Hyalina avena 


0.1 


- 


- 


0.08 


Miscellaneous 


1.1 


0.3 


2.7 


1.20 



11 



Average number of moUusks per lot of algae. 

12 

^'Gastropod species arranged in decending order of abundance. 



ASSOCIATIONS OF MARINE MOLLUSKS AND ALGAE 



173 






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(s;oi 02) 








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tus 
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5g 


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co^'s-<^öO e 


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t— ( 
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О 

5 w 



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174 



WARMKE AND ALMODOVAR 



О) 

ci 



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Ф 

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ш 

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и 

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а 

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тз 

с 

СИ 

тз 
о 
о, 

о 

V 

t-H 

CU 
Р4 



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••н 
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Average 

per lot 

on all 

Green 

Algae 

(50 lots) 


N CM (M N 

lOCMrHt-ioooocq 
ОСЭСЭСЭСЭСЭОСЭО 


tH 


W 

<: 
о 

<: 
о 

от 

и 

t-H 

и 
р< 

от 


(s;oi g) 

luniiaqv]/ 

Dd;opß 


со 

• 

о 


CO 


(s;oT g) 
глдцооц 

lUniUOlDOZllfU 






(s;oi g)l 

Sn}V}t4vD 

snufoiudd 


Ci 

1-1 


1-t 


im T) 

vpdmiiDjj 


я я 


о 


(s;oi gi) 

vtiumfo 
vpaiutiDfj 


(ЭООСЭСЭ СЭСЭСЭ 


CO 


(s;oT 9) 
8г84олоц4орьи 


^ сэ <э 


»-H 


(s;oT г) 

8дргоглю1щлд8 
vcfAdjnvj 






(s:^oт TT) 

V(¡Ad]nVQ 


1Л '^ тН СЧ1 
о о о (Э 




(s;oT г} 

VtJo/îSSVAD 






.(s;oT Í,) 
vjzmuacf 
5г8(}оХлд 


ю со 
,-í о 


c» 

• 

1-i 




Q 

G о 

йот 

ßi 


Braehidontes exustus 
Condyloeardia smithii 
Area imbricata 
Musculus lateralis 
Area zebra 
Barbatia eancellata 
Gouldia eerina 
Lima sp. 
Misc. young 


CO 
X5 

a 

Ü 

Ш 

1— 1 
0) 

r-H 

CTj 
-M 

О 

H 



CD 



CO 

c3> 



M 

W 

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и 

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о 

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и 

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> 



ASSOCIATIONS OF MARINE MOLLUSKS AND ALGAE 



175 



TABLE 8. Distribution of Pelecypods and Amphineura on 3 Species of Brown Algae^^ 





SPECIES OF ALGAE 




PELECYPOD 
SPECIES 


Dictyota 

bartayresii 

(19 lots) 


Dictyota 

divaricata 

(3 lots) 


Padina 

gymnospora 

(3 lots) 


Average per lot 

on all brown Algae 

(25 lots) 


Brachidontes exustus 
Barbatia cancellaria 
Musculus lateralis 
Miscellaneous 


1.58 
0.05 
0.05 
0.05 


6.0 




1.92 
0.04 
0.04 
0.04 


Total Pelecypods 


1.74 


6.0 




2.04 


AMPHINEURA 
SPECIES 


Ischnochiton sp. 


0.90 


0.67 


0.33 


0.80 



^ ^Average per lot. 



TABLE < 


). Importance of Red Algae as 


Habitats for MoUusks 














Average No. of 


Species of Red Algae^^ 


Gastropods 


Pelecypods 


Amphineura 


Total 


Mollusks per lot 


Coelothrix irregularis (2 lots) 


1,320 


6 




1,326 


663.00 


Centroceras clavulatum (3 lots) 


1,164 


9 




1,173 


391.00 


Acanthophora spicifera (20 lots) 


7,591 


35 


7 


7,633 


381.65 


Laurencia papulosa (18 lots) 


6,463 


68 


12 


6,543 


363.50 


Amphiroa fragilissima (5 lots) 


1,638 


12 


3 


1,653 


330.60 


Laurencia obhisa (11 lots) 


3,210 


1 


3 


3,214 


292.18 


Ceramiun nitens (9 lots) 


1,459 


4 




1,463 


162,55 


Hypnea musciformis (2 lots) 


317 






317 


158.50 


Spyridia filamentosa (5 lots) 


245 


20 


7 


272 


54.40 


Galaxaura lapidescens (2 lots) 


57 






57 


28.50 


Bostrychia tenella (1 lot) 


25 


1 




26 


26.00 


Hypnea spinella (2 lots) 


29 






29 


14.50 


Total on all red algae (80 lots) 


23,518 


156 


32 


23,706 


296.32 



Algae listed in order of importance. 



176 



WARMKE AND ALMODOVAR 



TABLE 10. Importance of Green Algae as Habitats for Mollusks 



Species of Alga^"^ 










Average No. of 


Gastropods 


Pelecypods 


Amphineura 


Total 


Mollusks per lot 


Cladophoropsis membranácea 












(6 lots) 


2,594 


9 




2,603 


433.83 


Halimeda opuntia (13 lots) 


1,606 


17 


16 


1,639 


126.08 


Caulerpa racemosa (11 lots) 


1,118 


12 


1 


1,131 


102.82 


Halimeda tridens (1 lot) 


48 


2 




50 


50.00 


Bryopsis pennata (4 lots) 


169 


7 




176 


44.00 


Penicillus capitatus (3 lots) 


106 


3 




109 


36.33 


Udotea flabellum {Z lots) 


89 


1 


1 


91 


30.33 


Rhizoclonium hookeri (5 lots) 


121 






121 


24.20 


Caulerpa sertularioides (2 lots) 


40 






40 


20.00 


Caulerpa crassifolia (2 lots) 


35 




2 


37 


18.50 


Total on all green algae (50 lots) 


5,926 


51 


20 


5,997 


119.94 



Importance of Brown Algae as Habitats for Mollusks 






Dictyota divaricata (3 lots) 
Dictyota bartayresii (19 lots) 
Padina gymnospora (3 lots) 


216 

836 

33 


18 
33 


2 

17 

1 


236 

886 

34 


78.67 
44.00 
11.33 


Total on all brown algae (25 lots) 


1,085 


51 


20 


1,156 


46.24 



^ 'Algae listed in order of importance. 



ZUSAMMENFASSUNG 
BEZIEHUNGEN MARINER MOLLUSKEN ZU ALGEN Ш PUERTO RICO 

Im Verlaufe einer Studie über auf Algen lebenden marine Mollusken wurde eine 
Gesamtzahl von 30 859, etlichen 90 Arten angehörigen Individuen von 155 Algenentnahmen 
aufgelesen, die 25der häufigsten Algenarten umfassten und aus der Strand- und Korallen- 
riffzone von La Parguera, Puerto Rico, stammten. Diese Weichtiere bestanden zu 99% 
aus kleinsten Gastropoden, au etwa3/4%aus Pelecypoden und zu etwa 1/4% aus Amphineu- 
ren. FQnfzehn Gastropodenarten bildeten 94% der gesamten Molluskenzahl. Rotalgen, 
mit einem Mittelwert von 296 Mollusken pro Probeentnahme, schienen der bevorzugte 
Wohnraum zu sein. Grünalgen, mit 120 Mollusken pro Probeentnahme standen an 
zweiter Stelle, während auf Braunalgen nur 46 Mollusken je Probe entfielen. 

Obwohl die meisten Molluskenarten auf jeder der Algengruppen aufgefunden wurden, 
so zeigten doch diese Weichtiere vielfach eine besondere Vorliebe für eine der Gruppen. 
Ja einige Arten zeigten sogar eine auffallende Vorliebe für eine spezifische Alge, 
wofür das beste Beispiel die Assoziation von Oxynoe antillanim mit der Alge Caulerpa 
racemosa. ist. 

Trotz der Häufigkeit dieser auf den Algen lebender kleinen Weichtiere zeigte unsere 
Studie dennoch 10 Arten auf, die bisher noch nicht aus Puerto Rico bekannt waren, 
nämlich: Amphithalamus vallei, Cyclostremiscus omatu3, Marginellopsis serrei, 
Assiminea succinea, Condylocardia smithii, Cyclostremiscus pulchellus, Cylindrobulla 
beauii, Peristichia agria sowie 2 unbenannte Arten von Omalogyra. 

RESUME 
ASSOCIATIONS ENTRE MOLLUSQUES MARINS ET ALGUES A PUERTO RICO 



Au cours d'une étude sur les mollusques marins vivant sur les algues à La Parguera, 
Puerto Rico, 30 859 individus, appartenant à quelque 90 espèces, furent trouvés sur 155 
lots d'algues de 25 espèces communes, qui furent recueillis dans la zone littorale et 
parmi les récifs de coraux. De ces mollusques, 99% étaient de minuscules gastéropodes, 



ASSOCIATIONS OF MARINE MOLLUSKS AND ALGAE 177 

environ 3/4% des pélécypodes et environ 1/4% des amphineures. Pour ce qui concerne 
les gastéropodes, 15 espèces formaient les 94% des mollusques recueillis. L'habitat 
favori semblait être fourni par les algues rouges, qui abritaient en moyenne 296 mol- 
lusques par lot. Les algues vertes venaient en second lieu avec 120 mollusques par 
lot tandis que les algues brunes n'hébergaient que 46 mollusques par lot recueilli. 

Quoique la plupart de ces mollusques furent trouvés sur chacun de ces 3 groupes 
d'algues, ces animaux montraient souvent une préférence pour l'un ou l'autre de ces 
groupes. Certaines espèces montrèrent même une préférence frappante pour une 
espèce particulière d'algue, dont le plus éclatant exemple est fourni par l'association 
d'Oxynoe antillarum avec l'algue Caulerpa racemosa. 

Dix de ces espèces de petits Mollusques n'étaient pas encore connus de Puerto Rico 
in dépit de l'abondance qu'ils y montrent sur les algues. Ce sont: Amphithilnmus 
vallei, Cyclostremiscus omatus, Margine Hops is serrei, Assiminea succinea, 
Condylocardia smithii, Cyclostremiscus pulchellus, Cylindrobulla beauii, Peristichia 
agria, ainsi que de 2 espèces non-determinées d'Omalogyra. 



RESUMEN 
ALGUNAS ASOCIACIONES DE MOLUSCOS MARINOS Y ALGAS DE PUERTO RICO 

Durante un estudio de moluscos marinos que viven sobre algas en La Parguera, 
Puerto Rico, un total de 30.859 individuos perteneciendo a alrededor de 90 especies 
fueron encontrados en 155 lotes de 25 especies de algas comunes colectadas en las 
zonas litoral y de arrecifes. De estos moluscos, 99% eran minúsculos gastrópodos, 
alrededor de 3/4% pelecípodos y 1/4 anfineuros. Quince especies de gastrópodos 
formaban el 94% de todos los moluscos colectados. Algas rojas eran el habitat favorito 
con un término medio de 296 individuos por lote. Algas verdes venían en segundo 
lugar con 120. Algas pardas dieron solo 46 moluscos por lote. 

Aunque la mayoría de las especies colectadas estaban presentes en todos los grupos 
de algas, en muchos casos mostraban preferencia por un grupo, y en unas pocas esta 
preferencia era decisiva por una alga específica, siendo el mejor ejemplo la asociación 
de Oxynoe antillarum con el alga Caulerpa racemosa. 

Entre los numerosos diminutos moluscos que se encontraron en las algas, 10 especies 
no habian sido indicadas previamente para Puerto Rico. Estas son: Ampkithalamus 
vallei, Cyclostremiscus omatus. Margine llopsis serrei, Assiminea succinea, Condvlo- 
cardia smithii, Cyclostremiscus pulchellus, Cylindrobulla beauti, Peristichia agria y 
dos especies aún no denominadas de Omalogyra. 

АБСТРАКТ 

НЕКОТОРЫЕ АССОЦИАЦИИ МОРСКИХ МОЛЛЮСКОВ И ВОДОРОСЛЕЙ 
В ПОРТО РИКО 
Герман Л. Вормкр и Луис Р. Алмодовар 

При изученииморских моллюсков, живущих на водирослях в районе Ля Паргу- 
эра, в Пуэрто Рико, всего было собрано 30,859 экземпляров, принадлежащих 
к 90 видам. Это количество было собрано со 155 водорослей, принадлежащих 
к 25 распространенным тут видам, собранным в литторали и в районе рифов. 
Из этого количества моллюсков 99^ были брюхоногие, около трех четвертей fo 
- двустворчатые и около четверти % панцырьные. Пятнадцать видов брюхоно- 
гих составили 94^ всех собранных моллюсков. Казалось, что красный водоросль 
был наиболее благоприятным жилищем, ибо в каждой его группе было найдено в 
среднем по 296 экземпляров. Коричневый водоросль дал только по 46 экзем - 
пляров с группы. 

Хотя большинство видов было собрано на всех группах водорослей, во мно- 
гих случаях животные показали предпочтение для определенных групп. Несколь- 
ко видов показали замечательное предпочтение к одному только виду водорос- 
ля, лучшим примером чего может служить ассоциация вида Охупое antillarum с 
водорослем Caulerpa racemosa. 

Несмотря на обилие этих мелких моллюсков на водорослях, в результате 
подсчета, были найдены 10 видов не найденные ранее в Пуэрто Рико. Эти ви- 
ды: Amphithalamus vallei, Cyclostremiscus omatus, Marginellopsis serrei, 
Assiminea succinea, Condylocardia smithii, Cyclostremiscus pulchellus, 

Cylindrobulla beauii, Peristicia agria и два новых вида рода Omalogyra. 



TAXONOMY AND ZOOGEOGRAPHIC RELATIONSHIPS OF THE 
SOUTH AMERICAN NAIADES (PELECYPODA: UNIONACEA AND MUTELACEA)! 

J. J. Parodiz and A. A. Bonetto 
Carnegie Museum, Pittsburgh, Pennsylvania, U. S. A. 

and 

Consejo Nacional de Investigaciones Cientificas 

Santa Fe, Argentina 

ABSTRACT 

A natural system of classification is proposed for the South American fresh-water 
pearly mussels which were formerly all grouped in the superfamily Unionacea. The 
systems recognized since the end of the last century which were based mainly on con- 
chological, and partly on anatomical characters, are here discussed in relation to recent 
embryological and phylogenetic research, especially as regards the structure and de- 
velopment of the different types of larvae. Researches made by the authors during the 
last decade have confirmed the existence of the "lasidium" larva, discovered by Ihering 
in 1891, but not observed since by other authors. This larva is typical of the South 
American genera Anodontites, Mycetopoda, Monocondylaea and Leila. At the same time 
the research of other workers on African species of Mutela has revealed the existence 
of a larva which, if not entirely similar to the lasidium, is similar in its basic structural 
features. Comparative studies of such structures and their development show a family 
differentiation between Mutelidae of Africa and Mycetopodidae in South America. On the 
other hand, the close relation between these two families, and their extraordinary embry- 
ological divergence from those other fresh-water mussels characterized by the well 
known "glochidium" larva, warrants the distinction of a new superfamily, MUTELACEA. 
All other South American fresh-water mussels with larvae of the glochidium type remain 
in UNIONACEA. 

The Mutelacea are living today in the southern hemisphere, excepting Australasia, 
Whether South American groups are derived from African groups, or vice versa, is not 
known. The anatomical and embryological differences between Mutelidae and the more 
advanced Mycetopodidae seem to indicate an ancient separation. Paleontological records 
are rare: none exist for Africa or Australasia; In North America, fossil casts from the 
Triassic of Pennsylvania were referred to by Pilsbry as a Mycetopoda -like mussel; 
Pleiodon priscus described by Ihering from the Cretaceous of Brasil is not a mutelid, 
as was assumed, but belongs to the genus Paxyodon (Hyriidae). Some references to 
Anodontites-\ik.e fossils from the Cretaceous of Bahia, Brasil are very doubtful. 

The South American Mutelacea, i.e., the Mycetopodidae, are divided into 3 subfamilies: 
Mycetopodinae, Anodontitinae and Monocondylaeinae; another subfamily, Leiliinae, might 
be accepted in view of more recent anatomical and embryological research. Other 
groups, at the subfamily level, indicated in previous classifications, cannot be main- 
tained, their characters being insufficient and the intergradations numerous. 

The South American Unionacea belong to the family Hyriidae, which also occurs in 
Australia but is absent in the rest of the world; the exclusively South American forms 
belong in the subfamily Hyriinae and are divided into 3 tribes: Diplodontini, Castaliini 
and Prisodontini. Especially the Diplodontini, largely formed by the genus Diplodon, 
are more closely related to forms of Australia and New Zealand, Here again, attempts 
to separate a number of subgenera have failed on account of the difficulty of defining 
constancy of characters. From the embryological point of view, however, we may dis- 
tinguish two entities of subgeneric value: Diplodon s.S., with parasitic glochidia, and 
Rhipidodonta with non-parasitic glochidia, i.e., having direct development. There is 
paleontological evidence of Hyriidae in the North American Triassic, the Paleocene of 
Southern Argentina, and the Eocene of Chile, the latter fossils being very similar to the 
species now living in the region as well as to related groups from Australia. All these 
fossils belong to the genus Diplodon, of which other species are known from the strata, 
at different levels of the middle and upper Tertiary, scattered over the continent of 
South America. 

The monotypic genus Bartlettia of the so called "fresh-water oysters", currently 
included within the Etheriidae, very probably belongs to a polymorph species of 
Mutelacea, Anodontites tenebricosus. Larval stages of Etheriidae are unknown, but 
further investigation may prove that the family, if it should be maintained as such, inte- 
grates with the Mutelacea. 

Comparative tables are given of the different systems of classification since 1900 as 
well as of the new system adopted here, from the superfamüy down to subgeneric level. 

^Research supported by a research grant, NSF-15032, to the senior author from the National Science Foun- 
dation, Washington, D. C, U. S, A. 

(179) 



180 



PARODIZ AND BONETTO 



The current system of classification of 
the Neotropical fresh-water mussels dates 
from the end of the last century, with im- 
portant improvements made during the last 
three or four decades (Table 3). Some ana- 
tomical characteristics favor the concept 
of a single family, Mutelidae, with many 
genera not only from South America, but 
also from Central America, Africa and 
Australasia. The anatomical similarities, 
however, are not consistently present, and 
embryological and conchological charac- 
ters, as well as Zoogeographie al factors, 
are at variance with that concept of single- 
ness. From the biological point of view, 
especially, the division of Mutelidae into 
Mutelinae and Hyriinae is fundamentally 
more distinctive than a separation at 
merely the subfamily level. 

In 1891 Ihering described a larval form, 
from one species of Mutelinae, Anodontites 
wymanni Lea (= A. patagónica Lamarck) 
which was entirely different from the 
"glochidium" larva until then considered 
common to all Unionacea. That type of 
larva, named "lasidium", has a body di- 
vided into three recognizable regions: the 
anterior, ciliated and somewhat conic or 
bell-shaped; the median, rounded and cov- 
ered by an indivisible shell, and the pos- 
terior, forming two short lobes with cirri 
or hooks placed in rows. Two peculiar 
ribbon-shaped appendages of considerable 
length evolve from the anterior end. 
Ihering later added the following remarks 
to the description: "I know this larva only 
in Glabaris [= Anodontites], but in Aplodon 
[=Monocondylaea], the anatomy and the egg 
agree so well that the larva can scarcely 
differ. It is advisable now, to follow further 
the distribution of this larva in America 
and Africa" (Ihering 1893: 59). 

Because of the remarkable differences 
between the two types of larvae and the 
fact that subsequent investigators failed to 
find, or to recognize, the lasidium, the 
existence of this larva remained doubtful, 
Its rediscovery was reported by Bonetto 
(1951) with a preliminary description of 
the lasidium of Anodontites trapesialis 
from the Parana River, and further in- 
vestigations revealed its presence also in 



Monocondylaea and Mycetopoda. The 
organization and development of the lasid- 
ium proved to be more complicated than 
could be inferred from Ihering's original 
diagnosis. Franc (1949) said that he found 
"glochidia" (I) in the gills of Mutela dubia 
and M. rostrata, but more recently (1959 
and 1961) Fryer of the East Africa Fisher- 
ies Research Organization, in Uganda, 
gave a complete description of the larva 
oi Mutela bourguignati, with important and 
detailed observations of its development. 
Its basic structure is that of a lasidium, 
although it is differentiated from the 
embryos of the South American genera by 
marked morphological features. 

COMPARISON OF THE LARVAE OF THE 

AFRICAN AND SOUTH AMERICAN 

"MUTELIDS" 

The African Larva 



The embryo described by Fryer from 
Mutela (Fig. 1) has the anterior end of the 
body divided into two short lobes. The 
second portion is covered by a single uni- 
valve shell, furnished at the end with two 
rows of 3-7 small hooks and a row of small 
spinulae. It develops while attached ex- 
ternally to the body of a fish, probably by 
means of the hooks. 

The larval shell is folded on the sides 
and fused at the median ventral line, 
forming an integral, not bivalved, piece 
(Fig. 2, LS ). This shell is uncalcified. 

As the larva grows, two tubular append- 
ages, called "haustoria" by Fryer, are 
produced anteriorly, penetrating into the 
fish's tissues and, apparently, acting as 
both trophic and fixing organs. After this 
the organism experiences a complete 
metamorphosis conducive to the organ- 
ization of the juvenile mussel, and finally 
the haustoria-base is cut, initiating the 
free living stage. The size of this larva 
is over 150 miera, almost twice as large 
as the lasidium known in the South Ameri- 
can species» Larval specimens of Mwíeía, 
kindly sent by Fryer, in different stages 
of development, allowed a more complete 
comparative study. 



SOUTH AMERICAN NAIADES 



181 





100 miera 



FIG. 1. Larva of Mutela bourguignati 
(Ancey) showing the long tentacle (from 
Fryer). 

The South American Larva 

Investigations on the lasidium of An- 
odontites trapesialis forbesianus {Lbsl) and 
its parasitic phase in fishes, revealed a 
coincidence of development with that of 
Mutela, but without formation of the tubu- 
lar appendages or haustoria indicated by 
Fryer. The larva is attached to the host 
by a cyst-like structure. 

The lasidium of Anodontites (Figs. 3-4) 
is smaller, measuring an average of 85 
miera or 56.6% of the size of the larva in 
Mutela. 

The two ciliated lobes of the frontal 
portion, already indicated by Ihering, have 
an elongate -conic shape, but it is obser- 
vable that the frontal portion can be sepa- 
rated into two circular pieces, lying side 
by side, and projecting shortly from the 
embryonic shell. This section coincides, 
in general, with that of Mutela. 

The filamentous appendages are very 
different. Ihering said that they consist 
of two wide flat ribbons emerging laterally, 



FIG. 2. Larva of Mutela bourguignati 
(Ancey), oblique-dorsal view (from Fryer 
1961, Fig. 3). CL ciliated lobes; LS 
embryonic shell. 

but in fact they seem to project from a 
more ventral position, in the portion half 
covered by the valve; they then expand, 
fused over the shell at the base of the an- 
terior ciliated lobes. Thus, a conic en- 
closure is formed, with the apex toward the 
anterior lower side of the larva. The upper 
margins of the ribbons remain free, 
forming a V-shaped canal extending about 
ten times the length of the larval body, and 
then dividing into two or three branches. 
Although the complexity of this process 
establishes a remarkable difference with 
Mutela, the position of the axes are es- 
sentially similar. 

These differences, however, are con- 
siderable reduced in Monocondylaea, in 
which the lateral expansions are less de- 
veloped, and also in Mycetopoda whose 
filament has no lateral expansions at all, 
as in Mutela. In Leila the lasidium differs 
from that of Anodontites by its larger size 
the ribbon-like appendages are narrower, 
become thinner distally and the cirri or 



182 



PARODIZ AND BONETTO 



line of folding 



anterior lobes 



cilia 



hooks 




posterior 
lobes 



embryonic shell 



organ of fixation 



25 miera 



FIG. 3. hdiSidium oi Anodontites trapezialis forbesianus {heâ). Dorsal view. 




FIG. 4. Same as Fig. 3, with division of the anterior lobes, and posterior lobes not 
visible (folded ventrally). 



SOUTH AMERICAN NAIADES 



183 



hooks of the posterior end are apparently, 
wanting. 

In the larval body, the outstanding 
characteristic in both African and South 
Americah forms is the uncalcified uni- 
valve shell (Fig. 5), whereby they differ 
essentially from the glochidia. The pos- 
terior end of the body is usually folded 
under the ventral side, and shows curved 
cirri or hooks (6-7 inAnodontites trape- 
sialis) forming a circle around a pair of 
lobes; additional spinulae like those in 
Mutela are absent. 

COMPARATIVE DEVELOPMENT OF THE 
JUVENILE MUSSEL 

The larva, inside the single, non-bi- 
valved enclosure follows divergent ways 
in Mutela and Anodontites . 

In Anodontites, the extremities are 
folded toward the center of the ventral 
side, while in Mutela the growth is longi- 
tudinal. The period of development is 25 
days in Mutela, but may be shorter or 
longer in Anodontites, 19 to 28 days. As 
a consequence of the differences in their 
parasitic adaptations, the young mussel in 
Mutela has an elongated body, regularly 
curved below and somewhat truncated 
anteriorly; in Anodontites it is short and 
high (Fig. 6) and the surface of the valves 
is formed by a series of planes, offering 
a polyhedral shape. Inboth cases the cuti- 
cle of the embryonic shell adheres to the 
valves of the juvenile mussel, and the small 
and cylindrical ligament is located on the 
middle of the hinge line, simulating a 
chondrophore. In the first stage the shell 
is composed only of conchiolin, but it is 
slowly filled in isolated spots with calcium 
carbonate. 

The internal organization is similar in 
both Mutela and Anodontites. The foot has 
a rudimentary byssogenous gland with its 
separate channel, but some elements of 
fixation indicated by Fryer for Mutela are 
not found in Anodontites; also, in the foot 
of the latter, there is a pair of very large 
otocysts. Both adductors are present. 
The branchiae, formed by 13 ctenidia in 
Mutela and 7 - 8 in Anodontites, are in a 



single row at each side; they develop from 
small papillae and are separated during the 
first days of life. The labial palps, di- 
gestive tract and heart do not differ. The 
mantle in Anodontites is closed from the 
beginning to form the siphons, which do 
not occur in Mutela. 

The ontogenetic processes in the African 
and the South American forms are of 
evident common ancestral relationship. 
They probably separated from all other 
Naiades with glochidia at a very early time 
in their evolution. On the basis of their 
marked differences a more natural system 
of classification can be established. 

TAXONOMIC CONSIDERATIONS 
(Compare with Table 3) 

Without discussing the very early essays 
of classification that were merely con- 
chological, and artificial in their results, 
it is necessary to return to Simpson's 
synopsis of 1896, for the first seriously 
founded system. 

Simpson distinguished two large fami- 
lies, Unionidae and Mutelidae, the first 
with schizodont hinge and glochidium lar- 
va, and the second with taxodont hinge 
(theoretically) and lasidium larva, thus ac- 
cepting Ihering's discovery, although it 
was yet unknown how many genera had 
this larva. The Unionidae included forms 
from all continents in different degrees 
of relationship, and Mutelidae confined to 
the Neotropical region and tropical Africa. 

Since then, from the intensive and valua- 
ble work of Ortmann, to the most recent 
speculations on classification, such as 
those of Modell, several systems have been 
proposed, but they only complement or 
modify that of Simpson. Ortmann grouped 
the neotropical and notogeic forms of 
Unionidae (equivalent to the "Lamphor- 
hamphus" group of Simpson), with the 
Mutelidae of Africa and South America, 
in a single family Mutelidae, based on 
anatomical details of certain relevance, 
and also because the marsupia for the incu- 
bation of the larvae were located in the 
inner laminae of the gills. He separated 
the Mutelidae into subfamilies Hyriinae 



184 



PARODIZ AND BONETTO 





25 miera 



FIG. 5. Larval shell oí Anodontites trapeziales, dorsal and lateral -ventral views, in 
the first day of parasitism on the fish Jenyssia lineata. 



posterior adductor ligament 



anterior adductor 



labial palps 



anal 
aperture 



branchiae 

branchial 
aperture 



margin of 
mantle 



granules of 
calcium 




larval shell 



juvenile shell 



byssogenous 
gland 



foot 



200 miera 



FIG. 6. Juvenile mussel oi Anodontites trapeziales ^ith new shell, and larval shell 
still attached. 



SOUTH AMERICAN NAIADES 



185 



and Mutelinae. 

The differences between the African, 
South American and all other known 
Naiades are so remarkable that in all 
probability they do not belong to directly 
related groups, but rather represent di- 
vergent ways in the conquest of continental 
waters. The two different types of larvae, 
i.e., glochidium and lasidium, cannot be 
considered to be derived one from the other 
or from any hypothetical direct ancestry. 
Ortmann's sound and critical observations 
of the the anatomical and conchological 
characters, add support to such a con- 
clusion. It is necessary to upgrade the 
taxonomic categories in the family group 
in order to adjust the system to our present 
knowledge. 



The most important, and the most over- 
looked, of Ortmann's taxonomical cons- 
siderations were his own reservations with 
regard to the stability of the system. He 
said in fact (1921:454) that: "It possibly 
might be advisable, in future, to elevate 
the two South American subfamilies to the 
rank of families...", and "the Mutelidaeoi 
Simpson (1900) correspond to our Mutel- 
inae" (p. 455 footnote). Pg. 567: "al- 
though closely allied to Spatha [=Mutela], 
the South American genera form a group 
by themselves, and the [only] similarity of 
Mycetopoda to Spatha in the anal opening 
apparently indicates only parallelism of 
development, no genetic relationship", and 
also (p. 568) that "According to our present 
knowledge, the two subfamilies are un- 



AdP 



AdA 



AdP 




AdA 




FIG. 7. Anatomy of South American and African naiad genera. Top, left: Anodontites 
(Mutelacea, Mycetopodidae); top right: Castalina (Unionacea, Hyriidae); below: Spath- 
opsis (Mutelacea, Mutelidae). A, anal opening; AdA, Adductor anterior; AdP, adductor 
posterior; B, branchial opening; E, elevator or dorsal scar; F, foot; EB, external 
branchia; IB, internal branchia; PI, palps; P, protractor; RA, retractor anterior; 
RP, retractor posterior; U, union of mantle separating anal and branchial openings. 



186 



PARODIZ AND BONETTO 



doubtedly allied; but they are very sharply 
separated by anatomical as well as shell- 
characters, and it is impossible to form 
an appropriate idea of their genetic con- 
nection". 

Regarding the condition of primitiveness 
in these groups, Ortmann remarks: "It 
is not very likely that the Mutelinae 
reached South America coming from 
Africa" (p. 455). "It is hard to say which 
group is more primitive, since of the two 
differing characters, the one (anal opening 
is more primitive in the American forms, 
the other (inner lamina of inner gill) more 
primitive in the African Spatha" (p. 567). 

These observations would have been 
sufficient to justify the separation, even if 
the system was based only on anatomy and 
not on theembryology of the larger groups. 
Ortmann used the study of the South A- 
merican larvae to diagnose species, some- 
times genera, but not at the family level. 
So it is that both lasidia and glochidia are 
included in his Mutelidae, although the 
larvae from African species were then still 
unknown and the South American lasidia 
continued unobserved after Ihering. 

The numerous genera developing through 
the embryonic stage of glochidium, are 
separated into several families, according 
to anatomical peculiarities, such as 
Margaritiferidae, Unionidae, andHyriidae. 
Consequently, the larval condition has a 
taxonomic value, not merely at the family 
but at the superfamily level. We have 
seen that, in the current system, it has 
only a minor importance, generic or spe- 
cific. We believe that adult mussels de- 
veloping from totally different embryos 
should not be in the same superfamily. 

In conclusion, the Superfamily UNIONA- 
CEA should be restricted to those groups 
with glochidium larva, and those with 
lasidium elevated to a new Superfamily 
MUTELACEA. 

A synoptic comparison of the two fami- 
lies which comprise the MUTELACEA, 
i.e., Mycetopodidae and Mutelidae, is given 
in Table I. 



THE SOUTH AMERICAN MUTELACEA 

The family Mutelidae is only known from 
Africa. In the New World they are replaced 
by Mycetopodidae, characterized by a 
hinge that is edentulous or has very rudi- 
mentary teeth; by a wide prismatic layer 
on the internal margin of the valves, the 
presence of a supra-anal aperture, the 
connection of the inner laminae of the 
branchiae with the visceral sac, and the 
absence of dorsal muscle scars. The dif- 
ferences between the lasidium and the las- 
idium-like larva of Mutelidae already have 
been indicated. 

In South America the two superfamilies 
Unionacea and Mutelacea, occupy over- 
lapping areas, though there are but 
marginal zones, having only the one or 
the other; these zones perhaps correspond 
to different origins and times of dis- 
persion. The Mutelacea (Mycetopodidae) 
are more restricted in their southward 
distribution (Map 1), occupying zones 
north, east and peripheral to the Pampas- 
Chaco districts, and some tributaries that 
cross these districts and empty into the 
Parana River. In the affluents of the left 
side of the Parana River the Mutelacea 
have a greater development than the Union- 
acea (Hyriidae) (Compare with Map 2). In 
the northwest they extend into Central 
America and Mexico, where the Hyriidae 
are absent. 

Invasion of northern forms into the lower 
La Plata River system probably occurred 
in relatively recent times (the basin as it 
is known today, was formed during the 
Pleistocene), through connection of tribu- 
taries of the Upper Paraguay with those 
of the Amazon, as is the case with Ano- 
dontites ensiformis. Only a single species, 
Anodontites puelchana (d'Orb.) is rarely 
found in northern Patagonia. No species 
are known west of the Andes, in Peru or 
Chile, a zone which is populated by 
Hyriidae of the genus Diplodon. 



SOUTH AMERICAN NAIADES 



187 



TABLE 1. Comparative Characters of Mutelacea 





Mycetopodidae 
(Neotropical) 


Mutelidae 
(African) 


Larva: 


lasidium 


lasidium-like but with 
different development 




with spinulae 


without spinulae 




parasites forming cysts 


parasites through tubular 
appendages 


Young mussel: 


with mantle closed 


with mantle open 




with more than 70 ctenidia 


with less than 20 ctenidia 




shell short 


shell elongated 


Inner laminae of gills: 


usually connected 
with abdominal sac 


free 


Dorsal scars: 


absent except in Leila 


single and well developed 


Anal opening: 


not closed above, 
except in Mycetopoda 


closed above, not forming 
supra -anal opening 


Hinge: 


toothless or single 
toothed, never taxodont 


taxodont when present 


Umbonal sculpture: 


absent or with concentric 
waves 


when present, rugose 
resembling some unionid 
types 


Distribution: 


South America except West 
side of the Andes and 
southern Patagonia; 9 genera 


Africa; 4 genera 


Fossils: 


North America, Triassic 
iJVIycetopoda ?); South 
America, Cretaceous- 
paleocene (Brasil) 


Pleistocene 



188 



PARODIZ AND BONETTO 




40 



Distribution of 
MYCETOPODIDAE 

in 
South America 



20 



MAP 1. Distribution of Mycetopodidae (Mutelacea) in South America. 



SOUTH AMERICAN NAIADES 



189 



Mycetopodidae are divided into three 
subfamilies: 

Mycetopodinae 

Edentulous shell very elongate and thin, 
gaping variably anteriorly. Prismatic 
layer narrower. Anal aperture with ten- 
dency to close above, and supra-anal not 
well defined. Foot extraordinarily long, 
cylindrical, ending in a knob, mushroom- 
like, protuberant. The lasidiumhasalong 
anterior filament and resembles that of 
Mutela more than those of other subfami- 
lies. 

Genera: Mycetopoda, Mycetopodella. 

Anodontitinae 

Shell edentulous, regular in shape. 
Valves not, or scarcely gaping. Peri- 
ostracum marked with creases and folds. 
Foot regular. Supra-anal aperture dis- 
tinct. Prismatic layer wide. Lasidium 
with very wide ribbon-like filament di- 
vergent at the distal end. 

Genera: Anodontites, Leila (see ap- 
pendix, p. 206). 

Monocondylaeinae 

Shell small, thick, solid and gaping. 
Hinge with one or two tuberculiform teeth. 
Periostracum with cloth-like sculpture. 
Prismatic layer wider. Supra-anal aper- 
ture and foot regular. Lasidium of an 
intermediate type between the other sub- 
families. 

Genera: Monocondylaea, Fossula, 
Haasica, Tamsiella. 

The family name Mycetopodidae has 
absolute priority, dating from Gray, 1840, 
and it was also used by Adams and Adams 
(1858) and by Carpenter (1861) («Mycetop- 
idae"). 

Anodontitinae and Monocondylaeinae 
were established by Modell in 1942. He 
restricted the subfamily Anodontitinae to 
the Anodontites, of the group crispatus- 
tenebricosus-clessini, and for the other 
species of the trapesialis groups, plus 



Leila, he created Glabarinae. Since 
Glabaris according to the majority of 
authors is a synonym of Anodontites such 
separation should be deferred until it may 
be based on better grounds. Recognition 
of mere groups of species in the Anodont- 
ites complex, as proposed byOrtmannand 
Haas, is more acceptable. Regarding the 
possible use of Leilinae, see appendix. 

FOSSIL MUTELACEA 

Paleontological evidence in Mutelacea is 
very poor. A single and very doubtful 
specimen was referred by Ihering (1912) 
to the Cretaceous of southern Brasil as 
Pleiodon priscus (discussed later). Pils- 
bry (1921: 36) described M>'ce¿o/)odad¿ZMc- 
uli from Triassic beds in Pennsylvania 
which also contain Diplodon: "While the 
generic reference of the fossil [M. 
diluculi] is not positive, the interior being 
unknown, its characters, so far as they are 
legible, agree well with Myceio/)oda, which 
appear to indicate this genus or one closely 
similar". Four other Anodontites -like 
species were described by Hartt (1870) 
and White (1887) under the generic names 
"Unio" and "Anodonta" for the Bahia 
Series of Brasil regarded as Upper Cre- 
taceous or possibly Pal eocene; these 
shells are smaller than the living Anodon- 
tites, the hinge area is unknown, and the 
generic identification uncertain; White 
suggested that some of them, A. mawsoni 
and A. allporti, may be Iridina, which is 
still less likely. 

Frenguelli (1945) described, among 
other fresh-water bivalves, several 
species of Paleonanodonta and Paleo - 
mutela, from Permian-Triassic strata of 
Patquia, Argentina. These genera are 
known from the Permian of South Africa 
and Russia, and do not seem to be directly 
related with modern types of Naiades of 
the family Mutelidae. These may be dif- 
ferent branches of fresh-water mussels 
evolved from marine ancestors which did 
not survive. 

Viewed in their distribution in the 
southern hemisphere, the Mutelacea agree 
with that zoogeographical pattern indica- 



190 



PARODIZ AND BONETTO 



live of a gondwanic originor, what Pilsbry 
(1911) called "Eogeic" fauna. In that "a- 
sylum", to apply the term given by Suess to 
his original concept of Gondwana, evolved, 
according to Pilsbry, several typical fami- 
lies of continental moUusks. However, the 
group from which these naiades arose is 
unknown; probably Mutelacea and Union- 
acea are not derived from a common stock 
but, even if they were, the groups separated 
at a very early time. 

Ihering emphasized the importance of 
Pleiodon [=Iridina] pris cus as an African 
element in the Brazilian Cretaceous, but 
the generic reference was questionable. 
The single fragment of the fossil valve 
figured by Ihering (1912), agrees more 
closely in umbonal and hinge characters 
with Paxyodon (type P. ponderosus Schu- 
macher, 1817 = Mya syrmatophora Gron- 
ovius, 1891, according to clarification 
and subsequent designation of Olsson and 
Wurtz, 1951). The hinge in Paxyodon 
seems to vary with development to a 
pseudotaxodont condition, which appears 
equally in Paxyodon ponderosus and 
Pleiodon priscus. Furthermore, Paxyodon 
belongs to Hyriidae and itsglochidiumhas 
been studied by Bonetto (1959). Thus the 
assumed relationship of Pleiodon priscus 
with African Mutelidae is unsound. The 
strata in which P. priscus was found proba- 
bly are younger than the indicated Bauru 
Formation of the Upper Cretaceous. 

NOTE ON THE GENUS BARTLETTIA 

The genus Bartlettia Adams, 1866 (type 
Etheria stefanensis Moricand), of which 
Rochanaia Morretes, 1941, is a synonym, 
currently is placed within the family 
Etheriidae which includes: Etheria from 
Africa, Pseudomuelleria from India and 
Acostaea from South America. 

Acostaea and Pseudomuelleria are 
monomyarians in the adult stage (only 
very juvenile individuals have two 
muscles); Etheria a.nd Bartlettia are di- 
myarians. The larval form of the Ether- 



iidae is still unknown. However, it is 
more probable that Bartlettia belongs to 
the Mutelacea^; close to, or included in 
the Mycetopodidae. Our personal obser- 
vations as well as those made by Carcelles 
(1940), Pain and Woodward (1961) and 
Yonge (1962), indicate that the young shells 
of Bartlettia are not distorted as the adult, 
but very similar to (sometimes undis- 
tinguishable from) Anodontites tenebri- 
cosus. Adults of A. tenebricosus de- 
veloping in crevices of rocky substratum 
(as shells living on the west bank of La 
Plata River commonly do) are strongly 
distorted and acquire the characteristic 
shape and aspect of Bartlettia. Also, the 
prismatic zone in both species is very si- 
milar and their distributions in southern 
South America are somewhat coincident. 
It is likely that Bartlettia stefanensis, 
recorded by Carcelles from the Paraquay 
basin, and A. tenebricosus belong to one 
and the same species. Acostaea is re- 
stricted to the Magdalena River in Colom- 
bia, and the fact that this species and 
Pseudomuelleria are mono-myarians is 
due perhaps to convergent evolution from 
their entirely sedentary life. 

THE UNIONACEA (HYRIIDAE) OF SOUTH 
AMERICA AND AUSTRALIA 

In 1896, Simpson related all the Aus- 
tralian forms of naiades to the genus Dip- 
lodon, assuming migration via Antarctica 
from South America. Ortmann (1912) con- 
cluded that the Australian naiades belonged 
to the subfamily Hyriinae, but did not 
establish any direct relationship among the 
genera. Iredale (1933/34) on tne contrary 
emphasized the differences, creating for 
the Australian forms the family Pro- 
pehyridellidae with four subfamilies: Vel- 
esunioninae without umbonal sculpture, 
Lortiellinae with ridged umbos, Cucumer- 
unioninae with plicate umbos and large 
shells, and Propeehyridellidae but within 
the Mutelidae (still including in this family 
the two types of embryos). They suggest 



^Modell (1949) tentatively placed Etheriinae as a subfamily of Mutelidae, and Bartlett- 
iinae between Anodontitinae and Mycetopodinae. 



SOUTH AMERICAN NAIADES 



191 



TABLE 2. Comparison of South American and Australian Hyriidae (Unionacea) 





South America 


Australia 


Marsupium with interrupted 








network of interlaminar 








comunications 




X 


X 


Marsupium with continuous 








network 




rare 


? 


Interlaminar connections of 








the non-marsupial branchiae 








obsolete 




X 


seems more developed 


Central orifice on diaphragm 








connecting cloacal and 




rare 




branchial openings 


{Diplodon solidulus) 


X 


Without orifice 




X 


rare 


Siphonal area pigmented 


(D. 


chilensis) 


variable, common 
in Hyridella 


Umbonal sculpture radial 




X 


rare, only posterior 



Umbonal sculpture with 
V- shaped ridges 



Umbo plicate or smooth 

Schizodont hinge strong 

Hinge with small teeth 

Glochidium triangular with 
a S-shaped tooth in each 
valve ending in 1 or more 
spines 

Glochidium with triangular 
tooth in each valve 

Without parasitic stage 

Heavy short shells with 
strong hinge 



less frequent 
{flyria and 
some Diplodon) 



rare 



rare 



Diplodon 
Paxyodon 



Tribe Castalini 
Rhipidodonta 

several Diplodon 



bars are radial 
common 

X 

rare 
common 



none 



rare 



192 



PARODIZ AND BONETTO 



filament 



mantle of larva 



larval tooth 




larval shell 



basal expansion 
of tooth 



sensitive 
hair brushes 



striation of 
shell margin 



marginated area of shell 



100 miera 



FIG. 8. Glochidium of Velesunio ambiguus (Philippi). Bogan River, Australia. 

Lateral view. 

distal extension 
of filament 



curved tooth 




tooth-base 
expansion 



Granulations of inner 
margin 

FIG. 9. Same as Figure 8. Internal view. 



SOUTH AMERICAN NAIADES 



193 



that the Australian naiades were derived 
from a basic stock of northern hemisphere 
ancestors which migrated to southwestern 
Asia in the Triassic; but a year later 
(1959: 243) McMichael and Iredale agreed 
that "an equally good case can be made 
for southern distribution across a temper- 
ate antarctic land mass". We understand 
this as referring to the Unionacea 
(Hyriidae) since no real Mutelacea are 
known from Australia. 

Modell (1942, 1949), segregated many 
groups on the basis of the umbonal struc- 
ture and hinge. In Mutelidae, which he con- 
sidered the most primitive, he included 
Velesunioninae and Lortiellinae, and he 
placed Cucumerunioninae in Margaritifer- 
idae and Hyriinae and Propehyridellinae 
in Unionidae. Also he indicated the origin 
of Unionidae andMargaritiferidaeasIndo- 
Pacific, whence the Hyridellinae invaded 
Australia, from where they moved to South 
America. This interpretation is incon- 
sistent with the fossil evidence of Hyriidae 

Summarizing our own observations, the 
differences and similarities of the Union- 
acea (Hyriidae) in South America and 
Australia, are outlined in Table 2. 

Classification of the Unionacea of the 
Southern Hemisphere is more complicated 
at lower taxonomic levels, especially since 
it seems to involve phylogenetic and zoo- 
geographical problems. However, our data 
are sufficient to establish the close re- 
lationship between the forms of South A- 
merica and Australia. Their affinités are 
closer than could be expected from di- 
vergence from common Eurasiatic an- 
cestors, even granting an extraordinary 
evolutionary stability combined with a 
high degree of parallelism. The dif- 
ferences are few and it is possible to out- 
line a lineage of Diplodon-Hyridella, sup- 
ported by recent researches in the glo- 
chidia. 

From Percival's description (1931) of 
the glochidium of DzpZodon lutulentus Gould 
(= Hyridella menziesi Gray, according to 
McMichael and Hiscock), that of D. 
menziesi hochstetteri (Dunker) by the 
same authors, and thela.rva.oiD. menziesi 
from one specimen in the Carnegie 



Museum collection (Fig. 16d), one can see 
that all these glochidia from the Australian 
region are entirely similar to those from 
South American species of Diplodon, in 
outline, shape, insertion and structure of 
the curved hooks. 




FIG. 10. Larval shell of Velesunio am- 
biguus (Philippi). 

The internal organization of the glo- 
chidia of many Australian species are not 
well known, but according to Percivalthey 
lack the larval filament and the sensitive 
cirri present in the majority of Diplodon. 
Hiscock (1951) andBonetto (1952) indicated 
the presence of such a filament in Veles- 
unio ambiguus (Fig. 8-10). 

An important variation in Velesunio is 
the basal expansion of the larval tooth 
over the free margin of the embryonic 
shell, and the presence of fine striae or 
crenulations along the same margin; its 
internal organization is, according to 
Bonetto, coincidental in general with Di- 
plodon, although the larval filament, short- 
er and hollow, shows two distal expansions 
absent in Diplodon. 

Except for these differences of detail, 
the glochidial phase in Diplodon and the 
Australian forms show greater similarity 
than that to be expected between Diplodon 
and other genera of South American Hyri- 
idae, such as Castalia, Castalina and 



194 



PARODIZ AND BONETTO 




100 miera 



FIG. 11. Glochidium of Diplodon delodontus delodontvs (Lamarck) Parana River, 
Argentina. (For nomenclature of the organs see Fig. 8). 




FIG. 12. Shell of the glochidium of Diplodon delodontus delodontus (Lamarck). 



SOUTH AMERICAN NAIADES 



195 




Map 2. Fossil Hyriidae. 1, Triassic Pennsylvania and Texas; 2, Paleocene southern 
Argentina (Patagonia); 2^, Paleocene southern Brasil; 3, Eocene Chile; 4, Miocene 
NE. Argentina; 5, "Upper Tertiary" (probably Pliocene), Argentina; 6, Pliocene Peru, 
Ecuador; 7, Pleistocene Buenos Aires. With exception of 2 (faxyodon) all other fossils 
belong to Diplodon. 



Callonaia. The number of similarities 
in the glochidia is the basis for separation 
of the family Hyriidae in the southern 
hemisphere from all the other Unionacea. 

FOSSIL HYRIIDAE 

The oldest known Diplodon are repre- 
sented by several species from the 
Triassic of Pennsylvania and Texas. An- 



other fossil group is found in the Paleocene 
and Eocene of South America (southern 
Argentina and Chile). All these fossils 
are generally smaller than most of the 
recent species (hence comparable to the 
hylaeus group), except for Eocene Chilean 
forms that differ very little from the 
living Diplodon patagónicas, a form which 
more resembles Australian species? 
From younger and different Tertiary 



За comparative study of the types and other materials of these fossil species, is the 
subject of a paper now in preparation by the present authors. 



196 



PARODIZ AND BONETTO 




MAP. 3. Distribution of Hyriidae in South America. 



SOUTH AMERICAN NAIADES 



197 






It 




^SE^ss^ 




300 miera 



FIG. 13. Left: Glochidium of Z)¿/)Zodon с/гаггмапм5, x2 10; right: Filament of the gill of the fish Яо/)/га5 
malabaricus (Characidae) (common name "tararira") of the Parana River, showing the cysts pro- 
duced by glochidia of Diplodon charruanus. 





FIG. 14. 



A. Juvenile mussel of Diplodon (Diplodon) charruanus xl66. B. Juvenile mussel of Di/Jiodon 
(fihipidodonta) burroughianus (= variabilis) showing the wide opening of the valves, xl95. 



198 



PARODIZ AND BONETTO 



levels, other fossil Diplodon are known 
from Colombia to southern Argentina, and 
several genera were proposed by Mar- 
shall: Prodiplodon, Eodiplodon, Ecuador - 
ea. Also Marshall's Antediplodon has 
subsequently been used for all the oldest 
species, despite the fact that no clear dis- 
tinction between this and other named 
genera, or even with Diplodon itself, has 
been established. Umbonal sculpture in 
Antediplodon is of the same type as that 
found in living species of the patagonicus - 
granosus group, as well as in other fossils 
of the late Tertiary. The hinge of Pro- 
diplodon singewaldi Marshall is similar to 
that of D. patagonicus . Some Triassic 
species such as borealis and pennsylvan- 
icus do not seem to agree with the type 
species of Antediplodon {Unio dumblei 
Simpson). The forms from the Paleocene 
of Patagonia, as well as Diplodon gard- 
nerae Marshall from the Pebas Formation 
in Peru, and the same type of Aníed¿/)Zoííon, 
resemble the group of hylaeus. The di- 
vision of the fossil species into genera 
as age-groups does not improve our tax- 
onomic knowledge and, if a vertical classi- 
fication or the maintenance of such names 
eventually becomes necessary, it has to 
be done on a more consistent basis. 

Pilsbry accepted the generic identifi- 
cation of the fossil species under D¿/)/oíion 
sensu lato, primarily from the only conspi- 
cuous character that these fossils show: 
the radially sculptured umbos, not present 
in other living or fossil North American 
"Unios''. This character was considered 
as primitive by Ihering, Marshall, Modell 
and Pilsbry himself. Ortmann, without 
giving to such character enough phylo- 
genetic significance, when diagnosing Di- 
plodon, stated, however, that: "the beak 
sculpture is the most important feature of 
the group". By the presence of radial 
sculpture in widely separated Triassic 
species, Pilsbry inferred (1921: 31) that 
North America once possesed a large and 
varied Naiad fauna of South American 
type. 

Comparison of the distribution of Terti- 
ary and living hyriid species in South 
America (Maps 2 and 3) shows that the 



expansion was from West to East, (earlier 
forms distributed along the Andes) and 
later especially from southwest to north- 
east between northern Patagonia and the 
rivers of the Parana system or their 
equivalents at the time. This type of dis- 
tribution is opposite to that oftheMyceto- 
podidae, which was from North to South 
in the East, without reaching the extreme 
southwestern areas long habited by Di- 
plodon. 

The rivers running across the Pampas- 
Chaco districts, tributaries of the Parana, 
are saltier than the tributaries from the 
East, a factor which seems to have re- 
stricted the dispersalof theHyriidae more 
than that of the Mycetopodidae. Another 
factor may be temperature: Diplodon is 
found in some cold bodies of water in 
which the Mutelacea cannot live, but 
systematized data are yet too poor to 
reach conclusions. 

Regarding the relationship of the recent 
South American and Australian Hyriidae, 
as indicative of an "Antarctic Way" of dis- 
persion, fossil evidence is lacking. 

THE GROUPS OF RECENT SOUTH 
AMERICAN HYRIIDAE 

The Unionacea of South America - and 
of Australia for the most part - form a 
well defined family, Hyriidae, with shells 
radially sculptured at the inner laminae 
of the internal branchiae that are in contact 
with the palps, and parasitic larvae with 
S-shaped teeth either ending in spinulae or 
strongly pointed, but always without ad- 
ditional denticulations, and without supra- 
anal aperture; nonparasitic glochidia may 
occur, without teeth, but in any case all 
the glochidia are perfectly distinguishable 
from those of the other families of Union- 
acea from the northern hemisphere. The 
prismatic layer is reduced to a fraction 
of millimeter, inconspicuous, or entirely 
absent. 

The family name Diplodontidae Ihering 
1901 (or Diplodont-inae Morretes 1949) is 
not valid, being preoccupied by Diplodont- 
idae Dall 1899, created for marine bi- 
valves. Prisodontini Modell 1942 included 



SOUTH AMERICAN NAIADES 



199 



lines of growth 



valve 



foot 



mantle 



adductor 




rim of mantle 



branchial 
filaments 



anus 



FIG. 15. Juvenile mussel of Diplodon {JRhipidodonta) variabilis (Maton). Ventral view. 



the genus Hyria {=Prisodon) which cannot 
be separated as a subfamily by itself. The 
name Hyriidae Swainson 1840 has priority, 
but Diplodontini and Prisodontini can be 
used as tribal denominations. 

The typical subfamily, Hyriinae, hasthe 
radial ribs on the umbo coalescent toward 
the center with very few exceptions, 
branchial diaphragm imperforated, anal 
aperture forming a simple groove without 
expansions, and the branchial aperture 
somewhat closed at the front. The glo- 
chidian tooth is triangular and not divided 
at the end. The glochidium is with or with- 
out larval filament, and the margin of the 
embryonic shells lacks crenulations. 

The South American Hyriidae can be 
divided into the follwing tribes: 



Tribe Diplodontini 

Shell regular in shape, not alate, always 
with radial ribs on the umbo, but of vari- 
able growth and posterior ridge scarcely 
developed, except in a few more elongated 
and more posteriorly acute forms, as in 
Diplodon parallelipipedon (Lea) or D. 
parodizi Bonetto. Branchial opening not 
entirely closed at the front. 

Glochidium subtriangular-scalene, with 
the teeth S-shaped, curved and ending in a 
pair of spinulae (Fig. 16, b, e,); larval 
filament long and rolled; with 2-4 sensi- 
tive cirri. Species of direct development 
have no teeth or hooks in the embryonic 
shell, but one, or several, marked bands 
of growth (Figs. 11-13). 



200 



PARODIZ AND BONETTO 




FIG 16 Glochidia oiHyriidae. a, b, c, e, South American; d, Australian, a, Callonaia; Ъ, Diplodon solid- 
ulus; c, Paxyodon alatus; d, Hyridella menziesi; e, Diplodon rotundus. All approximately x395. 




FIG. 17. Glochidium of Casíaízna psammo/ca (d'Orbigny) (for references see Fig. 8) . Parana River at 
Santa Fe. 



SOUTH AMERICAN NAIADES 



201 



Genus Diplodon. 
Tribe Prisodontini 

Shell subrhomboidal, bi-alate or álate 
only behind, but always with greater 
posterior expansion. Umbonal sculpture 
radial, very strong, with conspicuous 
coalescence of the vertical riblets; rarely 
the sculpture may be inconspicuous. Pos- 
terior ridge well marked. Branchial aper- 
ture as in Diplodontini. 

Glochidium triangular (isosceliform), 
with teeth less curved and shorter than in 
Diplodontini, ending in 2-3 needle-like 
points (the glochidium was studied in Paxy- 
odon alatus (Sowerby) (Fig. 16, c) but the 
internal organization is not yet completely 
known). 

Genera: Prisodon, Paxyodon. 

Tribe Castaliini 

Shell subquadrangular, solid, umbos 
elevated and umbonal cavity deep. Beak 
sculpture of variable development, some- 
times very obsolete. Branchial opening 
becoming perfectly closed at the front. 

Glochidium subtriangular, equilateral 
or isosceliform, with short, straight, tri- 
angular teeth, wide at the base but not 
divided at the end; cirri grouped in form 
of brushes; without larval filament (Fig. 
16, a; 17). 

Genera: Castalia, Cnstalina, Castal- 
iella, Callonaia. 

In the tribe Diplodontini the species pre- 
sent extraordinary ecological and indi- 
vidual variations, often repeated or mixed 
among the numerous local populations or 
demes, but without taxonomic value. Sub- 
generic divisions of Diplodon have been 
based on transitory shell characters only. 
The most reliable separation is based 
primarily on the parasitic or non-para- 
sitic condition of the larvae; secondarily 
groups of species may be recognized by 
shell characters, although this sometimes 
presents serious difficulties on account of 



the slow, intergrading, variations. Di- 
plodon rhiLacoicus (d'Orb.), for example, 
with a parasitic glochidium has been often 
confused from shell similarities with D. 
charruanus (d'Orb.) whose glochidium is 
non-parasitic; on the same account, D. 
charruanus is more closely related to 
the groups of D. hylaeus (d'Orb.) or D. 
variabilis (Maton) despite the shell dif- 
ferences. 

Species with parasitic glochidia belong 
to Diplodon sensu stricto. In the post- 
larval stage the juvenile mussel shows 
the hooks still attached and a long, ciliated 
foot (Fig. 14) which soon disappears (Fig. 
15). The non-parasitic species are in- 
cluded in the subgenus Rhipidodonta (type 
species Diplodon variabilis (= paranensis, 
burroughianus , bulloides), of which Cycl- 
omya, Bulloideus, Ecvuidorea and Schles- 
chiella are synonyms. In order to avoid 
the mistake of placing Rhipidodonta as 
"nomen oblitum" (introduced in Article 23, 
section b of the International Commission 
of Zoological Nomenclature Code of 1961), 
notice must be taken that, subsequently to 
its establishment by MSrch in 1853, itwas 
used by Adams and Adams, 1858, Fischer, 
1887, and Thiele, 1935. 

Ecuadorea Marshall 1932 was intro- 
duced for fossil forms of the very variable 
group of D. hylaeus, which is within the 
subgenus Rhipidodonta. 

Schleschiella Modell, 1950 is an as- 
semblage of unrelated species; its type, 
Diplodon burroughianus (Lea), is a syno- 
nym of D. variabilis (Maton), used by 
Mörch as type species of Rhipidodonta. 
This species has non-parasitic larvae of 
direct development, but Modell also in- 
cluded in Schleschiella (as a subspecies of 
burroughianus) the form rhuacoicus, which 
actually has a parasitic glochidium, as 
well as D. parallelipipedon. 

Although the numerous species of Di- 
plodon can be separated into minor 
"species-groups" for practical purposes, 
only the groups listed below can be 
diagnosed by some definite character- 
istics. 



202 



PARODIZ AND BONETTO 



Key to the genus Diplodon (Hyriidae) 



la. With parasitic glochidia, Diplodon 
s.s 2 

lb. Glochidia non-parasitic, Subg. Rhipid- 
odonta 3 

2a. Shell elongated, compressed laterally 
central costulae with marked con- 
vergence and tendency to cross, 
forming thick folds or nodules. Ex- 
ternal branchiae higher than the in- 
ternal and marsupia placed anteriorly 
Group of D. (D.) chilensis 

2b. Variable in length, diameter and alti- 
tude. Sculpture less convergent, not 
crossed. External branchiae of same 



height as the internal. Marsupia 
central or with posterior gravitation 
Group of D.(p.) rhuacoicus 

3a. Size and shape variable, generally 
more rounded. Sculpture less promi- 
nent and moderately convergent. 
Hinge teeth very variable in develope- 
ment Group of D. (Д.) variabilis 

3b. Small but very solid shells. Strong 
sculpture extended toward the middle 
of the shell or beyond. Several 
central convergent, chevron-like 
costulae. Hinge teeth thick and strong. 
Group of D. (Д.) hylaeus 



TABLE 3. COMPARAI 


nVE SYNOPSIS OF ( 


CURRENT CLASSIFICA 


nONS 


SIMPSON 


О RTM AN N 


HAAS 


MODELL 


1914 


1921 


1930/31 


1942/49 


Fam. UNIONIDAE 


Fam. МиТЕЬШАЕ 




Fam. HYRIIDAE 


Subfam. Hyriinae 


Subfam. Hyriinae 




Subfam. Hyriinae^ 


(Lamphorhamphus 








group) 








Tetraplodon 


Castalia 


Castalia 




Castalina 


Castalina 


Castalina 




Castaliella 


Castaliella 


Castaliella 


Antediplodon 


Callonaia 


Callonaia 


Callonaia 


Prodiplodon 


Diplodon 


Diplodon 


Diplodon 


= Schleschiella'^ + iossils: Eodiplodon 


(Cyclomya) 


(Cyclomya) 


(Cyclomya) 


+ Bulloideus Ecuadorea 


(ßulloideus) 




(ßulloideus) 


Castalioides 


Hyria 


Hyria 


Hyria 




(Triquetrana) 
Prisodon 


Prisodon 


(Triquetrana) 
Prisodon 


Subfam. 


r auDiam. 

Mutelinae^ 


ШуПапа) 






Prisodontinae 


Mutela 
+ Subfam. 
Iridininae^ 


Fam. MUTELIDAE 






Fam. MUTELIDAE ¡ 




Subfnm. Mutelinae 






Iridina 
Pleiodon 


Muiela 


Mutela 






+ Subfam. 

ТГ , 4 


Monocondylaea 


Monoconcylaea 


Monocondyla ea 
Diplodontites 


' 


Velesunionmae^ 
Velesunio 






Tamsiella 


■ = Monocondylaeinae^ 


Iheringiella 


Iheringiella 


Marshalliella 




Fossula 


Fossula 


Fossula 


^ 


Leila 


Leila 


Leila 


Subfam. Glabariinae^ 
\ + Glabaris 


Anodontites 


Anodontites 


Anodontites 


" 


(Virgula) 


(Lamphro- 
scapha) 


{Lamphro- 
scapha) 


Subfam. 

Anodontitinae^ 


(Steganodon) 








Mycetopoda 


Mycetopoda 


Mycetopoda 


Subfam. Mycetopodidae^ 
+ Mycetopodella 


4т1г:^и ~i^»u;^;,,«^ l r. 







5with Lasidium larva. 
^Lasidium-like. 
7See page 201 . 



SOUTH AMERICAN NAIADES 



203 



TABLE 4. SYNOPSIS OF PRESENT CLASSIFICATION 



MUTELACEA 



MUTELIDAE 



MYCETOPODIDAE -{ 



Africa 



UNIONACEA < 



HYRHDAE 



UNIONIDAE 



ANODONTITINAE 
MYCETOPODINAE 
MONOCONDYLAEINAE 
. LEILINAE^ 



iPrisodontini 
Castaliini 
Diplodontini 



VELESUNIONINAE, etc. 
L HYRIDELLINAE, etc. 



LAMPSILINAE 

ANODONTINAE 

UNIONINAE 



^ MARGARITEFERIDAE 



South 
America 



Australasia 



North 

America, 
Eurasia, 
Africa 



^See Appendix, page 206. 



204 PARODIZ AND BONETTO 

PRESENT CLASSIFICATION OF SOUTH AMERICAN NAIADES 
AND RELATED AFRICAN FORMS 

Superfamily UNIONACEA 

Families UNIONIDAE Fleming 1828 (with several subfamilies in the northern 
hemisphere) andMARGARITEFERIDAE Haas 1940^ (MargaritanidaeOrtmann 
1910) are not included in the Neotropical region (see Table 4). 

Family HYRIIDAESwainson(Hyria-nae) 1840; Herrmannsenl847 

= Hyridinidae Carpenter 1861; Diplodontidae Ihering 1901 non 
Dali 1899; Hyriinae Ortmann 1911. 

Type genus: Prisodon Schumacher 1817. = Hyria Lamarck 1819 
non Stephens 1829, Robineau 1863, Insecta; Яугга Gronovius 1763 
-Meuschen 1778 nomen nudum; Hyria Blainville 1821. 

Subfamily HYRIINAE Swainson 1840 (restricted South America) = Hyria-dae Agassiz 
1847; Prisodontinae Modell 1942, Morretes 1949. 

Tribe Prisodontini 

Genus Prisodon Schumacher 1817. = Naia Swainson 1840; Harmandia Rochebrune 
1881. 

Type: by subsequent designation of Olsson and Wurtz 1951: P. obliquus 
Schumacher. 

Subgenus Triplodon Spix 1827 

Type: T. rugosum Spix (= Hyria corrúgala Lamarck). 

Subgenus Triquetrana ? Simpson 1900. 
Type: Unio stevensi Lea. 

Genus Paxyodon Schumacher 1817. 

Type: P. ponderosus Schumacher = Mya syrmatophora Gronovius 1781. 

Tribe Castaliini 

Genus Castalia Lamarck 1819. = Tetraplodon Spix 1827. 

Type: Castalia ambigua Lamarck non Sowerby = inflata d'Orb. ? 

Genus Castalina Ihering 1891. 

Type: C. m.artensi Ihering. 



^The «Official List of Family-Group Names" [of the International Commission on 
Zoological Nomenclature] London 1958, p. 57, establishes: "Margaritiferidae Haas 
1940, Field Mus. Publ. (Zool) 24: 119, as validated under the Plenary Powers (type 
genus: Margaritifera Schumacher 1816)" [emend, of Margartifera]. The name 
Margaritiferidae was used previously by Henderson 1929; in 1936, however, Henderson 
used Margaritiferinae as a subfamily of Unionidae. 



SOUTH AMERICAN NAIADES 205 



Genus Callonaia Simpson 1900. 
Type: С duprei Simpson. 

Genus Castaliella Simpson 1900. 
Type: C. sulcata (Recluz) 



Tribe Diplodontini 

Genus Diplodon Spix 1827. = Iridea Swainson 1840. 
Type: Diplodon ellipticum Spix. 

Subgenus Rhipidodonta Mörch 1853. = Cyclomya Simpson 1900. Bulloideus 

Simpson 1900. Ecuadorea Marshall 1932. Schleschiella Modell 1950. 
Type: Unto variabilis Maton = paranensis + burroughianus Lea. 

Genus Diplodontites^^ Marshall 1922. 
Type: D. cookei Marshall 

Australian subfamiles HYRIDELLINAE and VELESUNIONINAE are known to have a 
glochidium larva; in Lortiellinae, Cucumerunioninae and Rectidentidae the larva is 
unknown. 

Superfamily MUTELACEA 

Family MUTELIDAE Gray 1847 (restricted to Africa). 

= Muteladae Conrad 1853; "Platiris I" group Lea; Iridinidae Bourguignat 
1886; Pliodontidae Rochebrune. 

Type genus: Mutela Scopoli 1777. =Spatha Lea 1838; Calliscapha Swainson 
1840; Mutelina Bourguignat 1855; Pseudomutela Simpson 1900. 

Family MYCETOPODIDAE Gray 1840 (restricted sensu Conrad 1853). 

= Mycetopidae Carpenter 1861. 

Type genus: Mycetopoda d'Orbigny 1835. 

Subfamily MYCETOPODINAE Adams and Adams 1858 (Mycetop-inae). 

Genus Mycetopoda d'Orbigny 1835 (JVIycetopus 1847). 
Type: M. silicuosa (Spix). 

Genus (?) Mycetopodella Marshall 1927. 
Type: M. /a Zcaia (Higgins). 



lOThe inclusion of this very little known genus, Diplodontites , within the Hyriinae is 
only tentative. It has a prismatic layer like a mutelid, and other characters approach 
Diplodon, but its embryology is unknown. 



206 PARODIZ AND BONETTO 

Subfamily MONOCONDYLAEINAE Modell 1942. = Monocondylae-idae Morretes 1949. 

Type genus: Monocondylaea d'Orbigny 1835. = A/)Zodon Spix (non Rafinesque 
1818). Spixioconcha Pilsbry 1893. 
Type: M. paraguayana d'Orbigny. 

Genus Haasica Strans 1932. = Marshalliella Haas 1931 (non Kieffer 1913, nec- 
Poppius 1914). Iheringiella Pilsbry 1893. Plagiodon Lea 1856. 
Type: Plagiodon balzani Ihering. 

Genus Fossula Lea 1870 

Type: Monocondylaea fossiculifera d'Orbigny. 

Genus Tamsiella Haas 1931 

Type: Monocondylaea tamsiana Dunker. 

Subfamily ANODONTITINAE Modell 1942. = Glabariinae Modell 1942. 

Type genus: Anodontites Bruguière 1792. = Patularia Swainson 1840; 
Glabaris Gray 1847; Styganodon Martens 1900; Ruganodontites Marshall 
1931; Pachyanodon Martens 1900. 

Type: A. críspala Bruguière 1^; 

Subgenus Lamphroscapha Swainson 1840. = Virgula Simpson 1900. 
Type: A. ensiformis (Spix). 

? Subfamily LEILINAE Morretes 1949 (See Appendix below). 

Type genus Leila Gray 1840. = Columba Lea 1833 (non Linnaeus 1758). 

Type: Anodonta blainvilleana Lea, 



APPENDIX 

New observations made on Leila blain- 
villeans (Lea) revealed a clearer dis- 
tinction from Anodontites . Leila has a 
pair of well devloped contractile siphons 
formed by a separate fold of the mantle 
and not by fusion of the mantle edges, and 
consequently a well marked palliai sinus. 
The palps are low and elongated instead 
of high and rounded a.s in Anodontites. The 
shell is more winged and gaping, with a 



series of 6 or 7 parallel dorsal scars which 
are not present in other Mycetopodidae, 
but represented in Mutela by a single one. 
The prismatic layer is practically absent. 

The lasidium of Leila is of a type 
closer to the larva of Mutela, of large size 
(three times larger than in Anodontites), 
with a long filament instead of a ribbon- 
like organ of attachment, the ciliated lobes 
well separated and without cirri at the 
posterior end. 

All these characters seem to indicate 



11 To this group, apparently, belongs Bartlettia stefanensis (Moricand). K, however, 
the previously supposed differences are sustained by further research on the 
Bartlettia-Acostaea group, then the name Bartlettiinae Modell 1942 should have 
priority. (See note on page 190). 



SOUTH AMERICAN NAIADES 



207 



that the differences between Anodontites 
and Leila are of an importance greater 
than previously assumed. Modell (1942- 
49) included Leila with his Glabariinae 
( = Anodontitinae in our scheme), but the 
genus constitutes rather a subfamily by 
itself, for which we have the name Leilinae 
Morretes 1949; that author, however did 
not indicate the reasons for the separation. 



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ZUSAMMENFASSUNG 

TAXONOMIE UND ZOOGEOGRAPHISCHE BEZIEHUNGEN DER SÜDAMERIKANISCHEN 
NAIADEN (PELECYPODA: UNIONACEA UND MUTELACEA) 

Für die südamerikanischen perlmuttrigen SUsswassermuscheln, welche früher alle 
in die Superfamilie Unionacea eingereiht wurden, wird hier eine natürliche Klassifi- 
kation vorgeschlagen. Die seit dem Ende des vorigen Jahrhunderts gebräuchlichen 
Systeme, die nach hauptsächlich konchyliologischen und nur teilweise anatomischen 
Richtlinien aufgestellt wurden, werden hier in Hinblick auf neuere embryologische und 
phylogenetische Forschungen besprochen, insbesondre was die Struktur und Entwicklung 
der verschiedenen Larventypen anbelangt. Untersuchungen der Autoren innerhalb der 
letzten 10 Jahre haben die Existenz einer "Lasidium" -Larve bestätigt, die seit ihrer 
erstmaligen Entdeckung durch Ihering im Jahre 1891 nie mehr beobachtet worden ist. 
Diese Larve ist für die südamerikanischen Gattungen Anodontites Mycetopoda, Mono- 
condylaea und Leila typisch. Gleichzeitig haben die Untersuchungen anderer Forscher 
an afrikanischen Arten von Mutela gezeigt, dass diese eine Larve haben, die, wenn sie 
auch nicht mit dem Lasidium identisch ist, ihm doch in den wesentlichen Strukturen sehr 
gleicht. Ein vergleichendes Studium des Aufbaus und der Entwicklung dieser Larven 
zeigt einen Rangunterschied von Familiengrad zwischen den Muteliden Afrikas und den 
Mycetopodiden Südamerikas an. Die nahe Verwandschaft dieser beiden Familien und 
ihre aussergewöhnlich auffällige Divergenz gegenüber denjenigen SUsswassermuscheln, 
die durch die wohlbekannte "Glochidium" -Larve gekennzeichnet sind, ermöglichen 
andrerseits die Aufstellung einer neuen Superfamilie MUTELACEA. Alle übrigen 
SUsswassermuscheln mit Glochidien verbleiben in den UNIONACEA. 



210 PARODIZ AND BONETTO 

Die Mutelacea leben heute in der südlichen Hemisphäre, mit Ausnahme von Aus- 
tralasien. Es ist unbekannt ob die südamerikanischen von den afrikanischen Formen 
abgeleitet sind oder umgekehrt. Die anatomischen und embryologischen Unterschiede 
zwischen den Mutelidae und den fortgeschritteneren Mycetopodidae scheinen auf eine 
frühe Trennung hinzudeuten. Paläontologische Aufzeichnungen fehlen beinahe völlig. 
In Nordamerika bezeichnete Pilsbry Fossilien aus den Triasformationen Pennsylvaniens 
als Myceiopoda -ähnliche Muscheln; "Pleiodon priscus", von Diering aus der Kreide 
Brasiliens beschrieben, ist nicht, wie angenommen, ein Mutelide, sondern ein Hyriide der 
Gattung Pexyodon. Verschiedene Angaben über Anodontite s-^nliche Fossilien aus der 
Kreide Bahias in Brasilien sind äusserst zweifelhaft. 

Wir teilen die südamerikanischen Mutelacea, d.h. die Mycetopodidae, in 3 Unter- 
familien ein: die Mycetopodinae, Anodontinae und Monocondylinae; eine weitere Unter- 
familie, die Leilinae, kann man vielleicht ebenfalls auf Grund neuerer embryologischer 
und anatomischer Erkenntnisse unterscheiden. Andere, in früheren Klassifikationen 
aufgestellte Gruppen mit Rangstufe einer Unterfamilie lassen sich nicht aufrechter- 
halten, da ihre Kennzeichen nicht genügend beständig und die Zwischenstufungen 
zahlreich sind. 

Die südamerikanischen Unionacea gehören der Familie Hyriidae an, welche auch in 
Australien vorkommt, aber auf der übrigen Welt fehlt. Die ausschliesslich süda- 
merikanischen Formen gehören der Unterfamilie Hyriinae an und werden in 3 Tribi 
eingeteilt: Diplodontini, Castaliini und Prisodontini. Insbesondre die Diplodontini, 
deren zahlreichste Vertreter der Gattung Dt/^Zocion angehören, sind näher mit den Formen 
Australiens und Neuseelands verwandt. Auch hier blieben Versuche die Gattung in eine 
Anzahl von Untergattungen zu zergliedern, infolge der Schwierigkeit beständige Merk- 
male zu definieren, erfolglos. Vom embryologischen Standpunkt aus kann man aber 2 
Einheiten von subgenerischem Wert unterscheiden: Diplodon s.S., mit parasitischen 
Glochidien und Rhipidodonta mit nicht parasitischen Glochidien, d.h. solchen mit 
direkter Entwicklung. Es gibt paläontologische Angaben über das Vorkommen von 
Hyriiden im nordamerikanischen Trias, im südamerikanischen Paläozän und im Eozän 
von Chile, wobei die letzteren Fossilien den heute in dieser Gegend lebenden Arten, 
wie auch verwandten australischen Arten, sehr ähneln. Alle diese Fossilien gehören 
zu der Gattung Diplodon, von welcher auch verschiedene andere Arten in jüngeren 
Schichten aus dem mittleren und oberen Tertiär des südamerikanischen Kontinentes 
vorkommen. 

Die den sogenannten "Süsswasseraustern" augehörige monotypische Gattung SaríZeííí'a, 
die man allgemeinerweise zu den Etheriiden rechnet, gehört walirscheinlich einer 
polymorphen Art der Mutelacea, Anodontites tenebricosus an. Die larvären Stadien 
der Etheriiden sind noch unbekannt. Höchstwahrscheinlich aber dürften weitere 
Untersuchungen ergeben dass diese Familie, i'alls sie überhaupt als solche erhalten 
bleibt, unter die Mutelacea einzureihen sein wird. 

Tabellen werden hier gegeben, welche die verschiedenen seit 1900 gebräuchlichen 
Klassifikationssysteme vergleichen und auch das hier angewandte System von den 
Superfamilien bis zu den Untergattungen zeigen, 

RESUME 

TAXONOMIE ET RELATIONS ZOOGEOGRAPHIQUES DES NAIADES DE L'AMERIQUE 
DU SUD (PELECYPODES: UNIONACEA ET MUTELACEA) 

Un système naturel de classification est proposé pour les moules nacrées fluviátiles 
qui étaient jusqu'à présent toutes rangées dans la superfamille Unionacea. Les systèmes 
en usage depuis la fin du siècle dernier, basés principalement sur des caractères 
conchyliogiques et partiellement sur des caractères anatomiques, sont ici discutés à 
la lumière de recherches embryologiques et phylogénétiques récentes, spécialement en 
ce qui concerne la structure et le développement des différents types larvaires. 

Les recherches faites par les auteurs pendant les 10 dernières années ont confirmé 
l'existence d'une larve, le ' lasidium', qui n'avait plus été observé depuis sa découverte 
première par Ihering en 1891. Cette larve est typique pour les genres sudaméricains 
Anodontites, Mycetopoda, Monocondylaea et Leila. Simultanément, des recherches 
faites par d'autres auteurs sur certaines espèces de Mutela de l'Afrique y ont révélé 
l'existence d'un type larvaire qui, s'il n'est pas exactement conforme au lasidium, en a 
néanmoins les traits structuraux essentiels. Des études comparatives sur l'organisation 



SOUTH AMERICAN NAIADES 211 

et le développement de ces larves permettent de formuler les différences entre les 
mutélidés de l'Afrique et les mycétopodidês de l'Amérique du Sud. D'autre part, les 
grandes affinités entre ces 2 familles ainsi que leur extraordinaire divergence embry- 
ologique d'avec toutes les moules fluviátiles caractérisées par les larves si bien 
connues du type "glochidium", permettent leur groupement dans une nouvelle super- 
famille, les MUTELACEA. Toutes les autres moules sudaméricaines à glochidies 
restent dans les UNIONACEA. 

Les Mutelacea vivent exclusivement dans l'hémisphère austral, sauf en Australasie. 
Nous ne sommes pas en mesure de juger si les groupes américains dérivent des 
groupes africains, ou vice versa. Les différences anatomiques et embryologiques entre 
les Mutelidae et les Mycetopodidae, plus évolués, paraissent indiquer une séparation 
ancienne. Nous ne disposons que d'indices paléontologique's fort restreints: ils font 
défaut pour l'Australie et l'Afrique; en Amérique du Nord Pilsbry attribue certains 
fossiles du triassique de Pennsylvanie à un genre ressemblant à Mycetopoda tandis que 
le "Pliodon priscus", décrit par Ihering du crétacé brésilien, n'est pas un Mutélidé 
comme on le croyait, mais un Hyriidé du genre Paxyodon. Enfin, certaines références 
à des fossiles du type de Anodontites, du Crétacé de Bahia au Brésil, sont fort douteu- 
ses. 

Les Mutelacea de l'Amérique du Sud, les Mycetopodidae, sont divisés en 3 sous- 
familles: les Mycetopodinae, Anodontinae et Monocondylaeinae, Une sous-famille 
additioneile, les Leilinae sera peut-être à introduire suivant les recherches récentes, 
mais il n'est pas possible de maintenir d'autres groupes, indiqués dans les classifications 
antérieures, au rang de sous-familles, car leurs distinctions anatomiques et conchyliolo- 
giques sont insuffisamment tranchées. 

Les Unionacea de l'Amérique du Sud appartiennent à la famille des Hyriidae, qui vit 
aussi en Australie, mais est absente du reste du monde. Les formes exclusivement 
sudaméricaines sont rangées dans la sous-famille Hyriinae et divisées en 3 tribus: les 
Diplodontini, Castaliini et Prosodontini, Les Diplodontini en particulier, dont le groupe 
le plus nombreux est formé par le genre Diplodon, sont les plus étroitement alliés aux 
formes australiennes et néozélandaises. Tous les essais de distinguer divers sous- 
genres ont échoué en raison de l'impossibilité d'en définir des caractères constants, 
même approximativement. 

Du point de vue embryologique, pourtant, nous pouvons distinguer 2 groupes de valeur 
sous-générique: Diplodon s.S., à glochidies parasites et Rhipidodonta à glochidies 
non-parasites, c'est à dire à développement direct. Nous disposons de renseigne- 
ments paléontologiques sur les hyriidés: des fossiles ont été décrits du triassique 
de l'Amérique du Nord, du paléocène de l'Argentine australe et de l'éocène du 
Chili, ces derniers étant très proches des espèces qui vivent actuellement dans 
la région, ainsi que des groupes apparentés de l'Australie, lous ces fossiles 
appartiennent au genre Diplodon, dont on connaît nombre d'autres espèces de différentes 
couches plus récentes des niveaux tertiaires moyens et supérieurs distribués de par 
le continent sudaméricain. 

Le genre monotypique Bartlettia, connu sous le nom de "huitres d'eau douce" et 
couramment inclus dans les Etheridae, fait très probablement partie d'une espèce 
polymorphe de Mutelacea, l'Anodontites tenebricosus . Les stades larvaires des Ethér- 
idés ne sont pas encore connus mais nous pensons que les recherches futures montre- 
ront peut-être que cette famille, si elle est maintenue, se rangera parmi les Mutelacea. 

Des tableaux comparant les différents systèmes de classification en usage depuis 
1900 sont ici donnés, ainsi que celui ici adopté, allant du niveau de la superfamille à 
celui du sous-genre. 

RESUMEN 

taxonomía y relaciones DE LAS NAIADES DE SUDAMERICA 

El presente trabajo propone una clasificación natural de las almejas nacaríferas de 
agua dulce sudamericanas que se agrupaban en la supe rf am ilia Unionacea. Los sistemas 
conocidos desde fines del siglo pasado, basados principalmente en caracteres concho- 
lógicos y en parte anatómicos, se discuten a la luz de recientes investigaciones embrio- 
lógicas y filogenéticas, especialmente acerca de la estructura y desarrollo de los 
diferentes tipos de larva que hasta ahora eran muy poco conocidos. 

Investigaciones llevadas a cabo por los autores en los últimos diez años han con- 
firmado la existencia de la larva "lasidio", que no había sido observada de nuevo desde 



212 PARODIZ AND BONETTO 

su descubrimiento por Iliering en 1891; esta larva es tipica de los géneros sudamericanos 
Anodontites, Mycetopoda, Monocondylaea, Leila y afines, Al mismo tiempo, otros 
estudios realizados en especies africanas de Mutela han revelado la existencia de un 
tipo de larva que, si bien no es exactamente igual al lasidio, participa del mismo plan 
de estructura. El estudio comparativo de la organización y desarrollo de estas larvas 
permite la diferenciación de dos familias, Mutelidae y Mycetopodidae, en Africa y 
Sudamérica respectivamente. Además, la estrecha relación entre esas dos familias 
y el extradordinario contraste de su embriología frente a las otras almejas cuyo tipo 
de larva es el bien conocido gloquidio, permiten agruparlas y distinguirlas en una 
nueva superfamilia MUIELACEA, mientras que los restantes géneros y familias se 
conservan en la superfamilia UNIONACEA. 

Las Mutelacea actuales son exclusivas del hemisferio sur pero ausentes en Austra- 
lasia. Un posible origen africano de los grupos sudamericanos, o viceversa, no ha 
sido demostrado todavía. Las diferencias embriológicas y anatómicas entre las 
Mutelidae y las más avanzadas Mycetopodidae parecen indicar una separación remota. 
Las referencias a hallazgos fósiles de Mutelacea son raras y carecen de confirmación: 
ninguna en África o Australasia; en Norte América se encontraron moldes, atribuidos 
por Pilsbry a Mycetopoda. o un género similar, en el 1 riásico de Pennsylvania; "Plei- 
odon priscos" descripto por Ihering del Cretáceo del Brasil, no es un mutélido como se 
había creído sino que pertenece al género Paxyodon de los Hyriidae, Otras referencias 
sobre almejas de tipo Anodontites del Cretáceo de Bahia, Brasil, son también muy 
dudosas. 

Las Mutelacea sudamericanas, Mycetopodidae, se dividen en tres subfamilias 
fácilmente reconocibles: Mycetopodinae, Anodontitinae y Monocondylaeinae; otra sub- 
familia, Leilinae, podria aceptarse basada en estudios más recientes. Ctros grupos 
al nivel de subfamilia intentados por previas clasificaciones no pueden mantenerse, 
por insuficiente caracterización y demasiada intergradación. 

Las Unionacea sudamericanas pertenecen a la familia Hyriidae, viviente también 
en Australasia pero ausente en otras partes del mundo. Aquellas que son exclusiva- 
mente sudamericanas forman la subfamilia Hyriinae, dividida en tres tribus: Diplo- 
dontini, Castaliini y Prisodontini; las Diplodontini, especialmente, están más relacion- 
adas con las formas de Australia y Nueva Zelandia; el grupo más numeroso es el 
género Diplodon, y, también aquí, previos intentos para distinguir subgéneros han 
fallado por la dificultad en definir caracteres constantes. Desde el punto de vista 
embriológico, sin embargo, se pueden distinguir dos grupos de valor subgenérico: 
Diplodon s.S., con gloquidias parásitas, y Rhipidodonta^ con gloquidias no parásitas, 
es decir con desarrollo directo. 

Fósiles de Hyriidae, todos pertenecientes al género Diplodon^ han sido encontrados 
en el T riásico de Norte América, (Pennsylvania y Texas), Paleoceno de Argentina 
austral y Eoceno de Chile, estos últimos ya muy parecidos a las especies actuales de 
la región así como a grupos actuales afines de Australia, Se conocen también otros 
fósiles del mismo género de otros niveles terciarios en diferentes localidades sud- 
americanas. 

El género monotípico Bartlettia, de las llamadas "ostras de agua dulce", corriente- 
mente incluido en la familia Etheriidae, muy probablemente pertenece a una especie 
polimorfa de Mutelacea, Anodontites tenebricosus. Estadios larvales de estos y otros 
Etheriidae son desconocidos, pero futuras investigaciones pueden comprobar que las 
Etheriidae, si deben mantenerse como tales, pertenecen a las Mutelacea, 

Se dan tablas comparativas de los diferentes sistemas de clasificación propuestos 
desde 1900, así como se presenta el sistema ahora propuesto, desde el nivel de super- 
familia hasta subgénero. 

АБСТРАКТ 

ТАКСОНОМИЯ И ЗООГЕОГРАФИЧЕСКОЕ РОДСТВО ШНОАМЕРИКАНСКИХ НАЯД 

Дж. Дж. Пароли с и А. А. Бонэтто 

Естественная система классификации предлагается для южноамериканских 
пресноводных жемчужниц, которые раньше были сгруппированы в сверхсемейство 
Unionacea . Системы, принятые в конце прошлого столетия, которые были бази- 
рованы главным образом на конхиологических и только отчасти на анатомичес- 
ких характерах, обсуждаются в связи с недавними эмбриологическими и филоге- 
нетическими исследованиями, в особенности же в связи со структурой и разви- 



SOUTH AMERICAN NAIADES 213 

тием различных типов личинок. Исследования, произведенные за последние 20 
лет, подтвердили существование личинки "ласидиум", найденной Ирингом в 1891 
г., но не наблюдавшейся с тех пор другими авторами. Эта личинка типична для 
южноамериканских родов Anodontites, Mycetopoda, Monocondylaea и Leila. В то 
же время исследования других работников африканских видов рода Mutela наш- 
лиличинку не совсем сходную с ласидиумом, но структурно близкую к нему в 
главных чертах . Сравнительное изучение этих структур и их развития показало 
семейственное сходство между Mutelidae Африки и Mycetopodidae Ккной Аме- 
рики. С другой стороны, близкое родство между этими двумя семействами и их 
чрезвычайно различное эмбриологическое развитие по сравнению с другими прес- 
новодными жемчужницами, для которых так характерна личинка "глохидиум", дик- 
туют их выделение в новое сверхсемейство MUTELACEA Все другие южноамерикан- 
ские пресноводные жемчужницы с личинкой типа глохидиум остаются в UNIONACEA. 

Виды сверхсемейства Mutelacea сегодня живут в южном полушарии, за иск- 
лючением Австралазии. Неизвестно, произошли ли южноамериканские группы от 
африканских, или наоборот. "Анатомические и эмбриологические различия между 
Mutelidae и более развитым семейством Mycetopodinae, повидимому, указыва- 
ют на их древнее разделение. Палеонтологические данные редки: и таковых 
не существует для Африки или Австралазии; в Северной Америке оттиски из 
триасовых пластов штата Пэннсильвании были отнесены Генрихом Пилсбри к жем- 
чужницам Mycetopoda; Pleiodon priscus, описанный Ирингом из меловых 
пластов Бразилии, не является мутэлидо'м, как это предполагали, но принад - 
лежит к роду Paxiodon (Hyriidae) Некоторые ссылки на ископаемые из меловых 
пластов в Бихии, в Бразилии, раковины вроде Anodontites очень сомнительны. 

Южноамериканские Mutelacea , т . -е Mycetopodidae разделяются на три под- 
семейства: Mycetopodidae , Anodotitinae и Monocondylaeinae; другое посемей- 
ство Leiliinae может быть принято в эту группу, судя по результатам недав- 
исследований его анатомии и эмбриологии. Другие группы на уровне подсемей- 
ства, указанные в предидущих классификациях, не могут быть удержаны из-за 
недостаточности их характеров и множества интерградаций. 

Ккноамериканские Unionacea принадлежат к семейству Hyriidae , которое 
находится также и в Австралии, но отсутствует в остальном мире; исключитель- 
но южноамериканские формы, принадлежащие к подсемейству Hyriinae , разделя- 
ются на три трибы: Diplodotini , Castaliini и Prisodontini. Подсемейство 
Diplodontini состоящее, главным образом из рода Diplodon, особенно близ- 
ко родственно австралийским и новозеландским формам. Тут снова попытка раз- 
деления его на подроды неудается, по причине трудности установить постоян- 
ство характерных черт. С точки зрения эмбриологии, мы можем различить два 
особых признака подродового значения: Diplodon ss., с паразитарной глохидией, 
и Rhipidodonta, с глохидией непаразитарной; другими словами, с прямым разви- 
тием. Есть палеонтологические данные о семействе Hyriidae в триасе Север- 
ной Америки, в палеоцене Ккной Аргентины и в эоцене Чили, ископаемые которо- 
го очень близки к видам ныне живущим в Чили, а также и к родственным группам 
в Австралии. Все эти ископаемые принадлежат к роду Diplodon, другие виды 
которого из пластов в различных плоскостях среднего и верхнего триаса, рас- 
сеяны по континенту Южной Америки. 

Монотипный род Bartlettia, так называемых "пресноводных устриц", теперь 
отнесен к семейству Etheriidae и очень возможно принадлежит к полиморфному 
виду Anodontites tenebricosus сверхсемейства Mutelacea. 

Сравнительные таблицы тут даны для разных систем классификации, начиная 
с 1900 года и кончая системой принятой нами, со сверхсемейства и до подродо- 
вого уровня. 



CLINES IN THREE SPECIES OF LAMPSILIS 
(PELECYPODA: UNIONIDAE) 

Alan M. Cvancara 
Museum of Paleontology, Ann Arbor, Michigan, U. S. A. 

ABSTRACT 



In relating the latitudinal position of three species of fresh-water mussels to shell 
measurements, an attempt is made to demonstrate a geographic north-south cline. 
Specimens used for this study range from northern Michigan southward to southern 
Alabama. Three shell measurement ratios: height/total length, width/total length and 
posterior length/total length, are plotted against the latitudinal position of specimens 
for each of the three species: Lampsilis ventricosa (Barnes) (121 specimens), L. ovata 
(Say) (79 specimens) and L. excavate (Lea) (60 specimens). Scatter plot diagrams indi- 
cate a trend of gradual shifting of points to one side or other of the diagram depending 
on the shell measurement ratio used. Diagrams of the shell ratios height/total length 
and width/total length show an increase in the ratio number as lower latitudes are 
approached. The posterior length/total length plot shows a decrease in the ratio number 
with lower latitudes. Some support for a cline is given in that the ranges of the three 
species overlap. The more northerly species, L. ventricosa and L. ovata, overlap in 
their respective ranges, and the range of L. ovata merges with that of the southern 
species, L. excavata. A statistical analysis of the data offers little to prove or disprove 
a cline. The concept of a cline, as suggested, raises the implication of a change in the 
taxonomy of the three species considered here. It is suggested that these nominal 
species are probably subspecies. A definite judgment must depend on confirmative 
studies based on soft part morphology and cross-fertility experiments. 



INTRODUCTION 

A gradual change in some character over 
large areas has been noted in many animal 
groups. This character gradient or cline 
has even led some workers to formulate 
"rules", which, in a general way, can be 
applied to express gradual geographic 
variation (for summary of rules, see Mayr, 
1942: 88-94). The purpose of this paper 
is to demonstrate a regional cline in fresh- 
water mussels (family Unionidae), which, 
as far as the writer is aware, has not been 
done previously. 

Clines in moUusks, in general, are 
rather well-known (examples in Clench, 
1954: 122-125 and van der Schalle, 1948: 
p. 26-30 and p. 57-60). However, clines 
reported in naiads are few, and these may 
be termed ecoclines (Huxley, 1938, p. 219). 
Ortmann (1920: 269-312) found that in 
certain mussels of the upper Ohio 
drainage, obesity (length of shell divided 
by diameter or width) increases gradually 
in a downstream direction. Stated in an- 



other way, shells are more obese (swollen) 
downstream in the larger rivers and less 
obese (compressed) in the headwaters. 
Ball (1922) statistically analyzed obesity 
and size of stream and arrived at the same 
conclusions as Ortmann. 

This study is an analysis of a cline of 
regional extent and is based on shell 
measurements of river naiads which range 
from northern Michigan southward to 
southern Alabama. The specimens used 
are from an area bordered approximately 
on the east by the Applachian Mountains 
and extending west to eastern Kansas. 
Three species of Lampsilis (subfamily 
Lampsilinae) were chosen for the study 
because they are suspected of forming a 
closely related group: L. ventricosa 
(Barnes), L. ovata (Say) and L. excavata 
(Lea) (Fig. 1). They are typically de- 
veloped, as follows: 

Lampsilis ventricosa (Barnes); shell 
subovate to subelliptical; beaks high and 
sculptured with few coarse irregular 



(215) 



216 



A. M. CVANCARA 





50 mm. 

_J 




FIG. 1. Comparison of the left valves of three species of fresh-water mussels: Lampstlts ventrt- 
cosa (Barnes), A (UMMZ 165196), Grand River, Michigan; L. ovata (Say), В (UMMZ 86356), Wabash 
River, Indiana; L. excávala (Lea), С (UMMZ 65656); Cahaba River, Alabama. All specimens are of approxi- 
mately the same age, each having 5+ annulae. 



CLINES IN LAMPSILIS 



217 



ridges; posterior ridge low or wanting 
(upper Mississippi drainage; in lati- 
tudinal extent from about northern Mich- 
igan to northern Illinois). 

Lampsilis ovata (Say); like L.ventricosa 
but with strong, well-developed pos- 
terior ridge (Kentucky and Tennessee). 

Lampsilis excávala (Lea); with well- 
developed posterior ridge but smaller 
than L. ventricosa andL. ovata (Alabama 
River system). 



MATERIAL AND METHODS 

Shell measurements used in the present 
study are (Fig. 2): 

Total length - greatest length measured 
parallel to the hinge line. 

Posterior length - distance from pos- 
terior end of shell to point of beak, 
parallel to hinge line and measured on 
interior of left valve. 




FIG. 2. Left interior (left) and anterior (right) views of Lampsilis ventricosa (Barnes) 
showing where shell measurements were taken., 



218 



A. M. CVANCARA 



Height - distance at right angles to hinge 
line at highest part of umbo. 

Width - distance across both valves, 
measured at same relative position as 
height. 

Another measurement, the distance 
between the outer edges of the adductor 
muscle scars (DAS) measured parallel to 
the hinge line, was also made on all speci- 
mens. However, this measurement does 
not appear significant, as is mentioned 
again in the Discussion. All measurements 
were made with vernier calipers. 
Measurements from the shell interior 
were obtained by fixing the shell to the 
back of a framed plate glass by stiff rubber 
bands. Desired distances were trans- 
ferred through the glass on paper with 
triangle and T-square and then measured 
with calipers. 

Since all three species involved here are 
sexually dimorphic, care was taken to 
measure specimens of the same sex, i.e., 
males. Male shells have a somewhat 
pointed posterior end, whereas the pos- 
terior end in females is bluntly truncated 
and the postero-ventral part is more in- 
flated. To maintain relative size within 
and between all three species, only river 
forms were measured;lake forms are often 
typically stunted. Also, in this study are 
included only those specimens which have 
four annulae or more. All specimens 
measured are in the collections of the 
Mollusk Division, Museum of Zoology, 
University of Michigan. 

From the measurements of the 260 
specimens {Lampsilis ventricosa, 121, L. 
ovata, 79, L. excavate, 60), various shell 
ratios were computed: height/total length, 
width/total length, posterior length/total 
length, distance between outer edges of 
adductor muscle scars (DAS)/total length, 
and width/height (these data are on file in 
the Mollusk Division, Museum of Zoology, 
University of Michigan). These ratios were 
then plotted against the latitudinal position 
of each specimen. Of five ratio plots con- 
structed, three are presented here: height/ 
total length, width/total length and pos- 



terior length/total length (Figs. 3, 4, 5). 
Each point on the three grades represents 
a single specimen. In some localities the 
spread of several points on a given lati- 
tude gives some idea of station variation. 

DISCUSSION 

It can be seen that points on the scatter 
plot diagrams (Figs. 3, 4, 5) show a trend 
of gradual shift to one side or the other 
with a change in latitude, depending on the 
measurement ratio used. The gradual shift 
seems to indicate quite clearly a gradual 
change in a measurable character, i.e., a 
с line. Additional support for the concept 
is given in that the three species overlap 
in their geographic ranges. The range of 
the northerly species, Lampsilis ventri- 
cosa and L. ovata overlap, and the range of 
L. ovata merges with that of the southern 
species, L. excavata. The с linal situation 
also seems to be reflected in certain physi- 
cal factors of the shell. As pointed out 
earlier, L. ovata, as well as L. excavata, 
typically differ fromL. venin cosa in the 
possession of a well-developed posterior 
ridge, which is low or completely lacking 
in the latter species. However, the de- 
velopment of this ridge in L. ventricosa 
and L. ovata is gradual and intermediate 
in strength in certain areas where the two 
species occur together. Another gra- 
dational character appears to be size. Al- 
though no statistical proof has yet been 
compiled, there seems to be a gradual 
decrease in size within the three species 
from north to south. 

In a way, it seems rather surprising that 
a gradual trend is indicated by shell 
measurements of specimens over an area 
of regional extent. One might expect local 
environmental effects to "mask", more or 
less, any regional trend which might be 
present. Some idea as to the effect of 
habitat on size, shape and other characters 
on mussel shells is given by Ball (1922: 
93-97, summary of observations by earlier 
workers). 

The shell ratio height/total length (Fig. 
3) seems to show the most uniform shift 
of points, with an increase in the ratio 
number as lower latitudes are approached. 



CLINES IN LAMPSILIS 



219 



= -.576 



• • •' 



▲ .A AJ^AA 



И 


^Atí 




A 




"M 


A 


i-4 

A 
A^ 








• 


Lan 


psi 


is 


ventricosa 




■ 


Lan 


psi 


¡s 


ovata 




A 


Lan 


ipsi 


is 


excavato 



.600 .650 .700 .750 .800 .850 

HEIGHT / TOTAL LENGTH 

FIG. 3 



.556 



J 



A .A AA A. 



• Lampsiiis ventricosa 

■ Lampsiiis ovota 

A Lampsiiis excavólo 



.400 .450 .500 .550 .600 

WIDTH / TOTAL LENGTH 

FIG. 4 



FIG. 3. Scatter plot of height/total length of shell to latitude in three species of fresh 
water mussels. Latitudinal limits of various states are given only for orientation; shells 
from states other than those given are also included in the plot. 

FIG. 4. Scatter plot of width/total length of shell to latitude in three species of fresh- 
water mussels. Latitudinal limits of various states are given only for orientation; shells 
from states other than those given are also included in the plot. 



220 



A. M. CVANCARA 



• • • • 



* I* 






. ,:•■■.■ ••• 



34 - 


A 


A 


A 






\ 




A 


A 


A^ 


'a 


A 
*■ A 




33°- 


Л 


A_A'4 

JaÍ 

A . 

A 


AA 
iA A 


A 


< 

< 

i 


32°- 






A 


AA 


• Lompsilis 


3 

veniri coso 


зГ- 






A 




■ Lompsilis 


ovoto 


3 0° 










A Lompsilis 


excavota 








1 


' 


1 1 



.550 .600 .650 .700 .750 .800 

POSTERIOR LENGTH / TOTAL LENGTH 

FIG. 5 



FIG. 5. Scatter plot of posterior length/total length of shell to latitude in three species 
of fresh-water mussels. Latitudinal limits of various states are given only for orien- 
tation; shells from states other than those given are also included in the plot. 



CLINES IN LAMPSILIS 



221 



This would indicate a decrease in total 
length of shell relative to height with more 
southerly formso The shell ratio width/ 
total length (Fig. 4) gives a similar in- 
crease in ratio number with the approach 
of lower latitudes, indicating a gradual 
decrease in total length relative to width. 
The points on this plot, however, appear 
more widely scattered, indicating that 
width is a more variable measurement than 
height (Fig. 3). 

Part of this apparent variability may be 
due to using shells of rather variable age. 
Ball (1922; 118) pointed out that younger 
shells are more obese (swollen) than older 
ones in the species he considered. How- 
ever, this does not seem to be the case 
with the three species considered here, at 
least as can be determined from those 
localities where several specimens were 
measured. The width/total length plot 
also differs from the preceding one in that 
the points representing Lampsilis excá- 
vala are rather markedly "skewed" toward 
the side of higher ratio numbers, and 
show a break from the general trend. The 
reason for this difference, at present, is 
unknown. 

Figure 5 shows a plot of the ratio pos- 
terior length/total length which gives a 
general trend of lower ratio numbers with 
lower latitudes. These measurements re- 
flect a change in the position of the beak, 
and they indicate that a more centrally 
located beak occurs in the more southerly 
specimens. This plot also appears to show 
that the points for Lampsilis excávala are 
slightly skewed, in this case toward lower 
ratio numbers. 

Two other shell measurement ratios 
were analyzed, but they are not shown here 
in graphic form; these were width/height 
and DAS/total length. The width/height 
plot was very similar to the width/total 
length plot (Fig. 4) with points for L. ex- 
cávala skewed somewhat more markedly 
toward higher ratio numbers. A plot of 
DAS/total length showed no apparent trend, 
a condition taken to mean that the position 
of the adductor muscle scars is not signi- 
ficant and is probably a mechanical factor. 
A long shell would require adductor 



muscles to be spaced farther apart for 
effectively closing the two valves, with 
the reverse being true in shorter shells. 

STATISTICAL ANALYSIS OF DATA 

Regressions were computed for three 
shell measurement ratios on latitude, for 
each species separately, and also for all 
three species taken together (Table 1). 
For the height/ total length and width/total 
length vdiiiosoi Lampsilis ventricosa there 
is a significant correlation at the 95 
percent significance level, indicating a 
change of ratio number with latitude. For 
the posterior length/total length ratio of 
L. venlricosa there is little, if any, corre- 
lation. Lampsilis ovala and L. excávala 
show, from the correlation coefficients, 
essentially no correlation, for each of the 
ratios analyzed. Two interpretations can 
be given for the data of the latter two 
species: (1) there is actually no change in 
any of the ratio numbers with a change 
in latitude; (2) the latitudinal distribution 
in each of the two species is too limited 
to indicate a change, although one may be 
present. 

Regressions computed for the three 
species taken together produce relatively 
high correlation coefficients for all three 
shell measurement ratios, indicating a 
rather significantly high correlation or 
change with latitude. 

However, these data should be treated 
with some reservation. A high correlation 
coefficient could be obtained for three 
populations widely separated latitudinally 
and in some specific measured character» 
That is, there could be plots of three 
clusters of points, separated along one 
axis by a difference in latitudinal range 
and along the other axis by a difference in 
some measurable character. If these 
clusters were more or less offset, en 
echelon, there would result a relatively 
high correlation coefficient and a re- 
gression line would pass through the three 
separated clusters of points. If there is 
a valid correlation for all species taken 
together, it would point out that sufficient 
latitudinal range is needed for the corre- 



222 



A. M. CVANCARA 



TABLE 1. Statistical data of three shell measurement ratios for Lampsilis ventricosa, L. ovata, and L. 
excávala. Numbers written as exponents and subscripts to the correlation coefficient (r) in- 
dicate the 95 percent confidence interval on r. 



Species 
and shell measurement ratios (X) 



Lampsilis ventricosa 

Height/total length 

Width/total length 

Posterior length/total length 
Lampsilis ovata 

Height/total length 

Width/total length 

Posterior length/total length 
Lam,psilis excávala 

Height/total length 

Width/total length 

Posterior length/total length 
All 3 species of Lampsilis combined 

Height/total length 

Width/total length 

Posterior length/total length 



Correlation 
coefficient 
(r) 



-.346 



-.379 



+.088 



-.179 
494 

-.179 
522 

-.092 

+.262 



+.050 



.014 



+.139 



•.173 
-.268 
+.208 
234 
-.085 
+.350 



+.007 



-.013 



.067 



.576 



-.556 



Number 



.247 

+.260 

+.208 

266 

+.190 



+.458 



-.315 



-.488 
-.652 
-.466 
-.635 
+.359 
+.549 



121 



79 



60 



Arithmetic 
Mean {x) 



260 



.6912 
.4453 
.6732 

.7291 
.4416 
.6508 

.7533 
.5371 
.6268 

.7170 
.4653 

.6557 



Standard 
Deviation 
(Sx) 



.03736 
.04731 
.03384 

.03316 
.01553 
.02922 

.03501 
.03782 
.02730 

.04380 
.05735 

.03609 



lation to appear. It would then follow that 
the significant correlation of Lampsilis 
ventricosa for the height/total length and 
width/total length ratios is merely additive 
to the more extensive trend. It is con- 
cluded that the statistical analysis offers 
but little proof or disproof of the thesis 
presented here, 

CONCLUSIONS 

The attempt to analyze the clinal possi- 
bilities as they relate to three nominal 
species of fresh-water mussels, Lamps- 
ilis ventricosa (Barnes), L. ovata (Say) 
and L. excávala (Lea), stems from the 
practical problem one faces when names 



are to be applied to this group. It has been 
a common experience to label northern 
forms L. ventricosa; that is, those forms 
found in the upper Mississippi River drain- 
age (in latitudes encompassing New York, 
northern Ohio, Michigan, Wisconsin, and 
northern Illinois). On the other hand, 
specimens from Kentucky and Tennessee 
would be considered "southern" and with 
their more centrally placed beaks and their 
high and well-developed posterior ridges, 
these forms are identified as L. ovata. 
But in such intermediate areas as southern 
Ohio and Illinois intergrades are common 
and they have usually been named L. ovata 
ventricosa. As for L. excávala, it seems 
to have most of the characteristics of L. 



CLINES IN LAMPSILIS 



223 



ovata with respect to the more central 
position of the beaks and the prominent 
high posterior ridge; it varies essentially 
in being consistently smaller in size than 
L. ovata. In distribution L. excávala is 
part of the fauna of the Alabama River 
system; its differences probably reflect 
a change brought about since the time the 
Alabama and Tennessee drainages may 
have been connected. 

Indication that a cline exists among 
Lampsilis ventricosa, L. ovata and L. 
excavata, based on shell measurement 
ratios, raises some doubt regarding the 
taxonomic status of these three species. 
One would naturally suggest that these 
species could be represented by sub- 
specific taxa. If so, various possibilities 
come to mind; for example, the three 
groups could be treated as separate sub- 
species of a single species complex. On 
the other hand, the L. ovata ventricosa 
complex is already recognized as quite 
intimately related so that it could be 
separated subspecifically from the south- 
ern form, L. excavata. It is also possible 
to use taxa of lesser rank, but this approach 
does not seem warranted here. It must 
be emphasized that the taxonomic charac- 
ters used are only those of shell measure- 
ment ratios and that only the shells of 
these animals were examined. Much work 
remains on the anatomy of the animals 
and the с ros s -fertility among these three 
species has not been studied. The recog- 
nition of the possibility that a cline exists 



may be helpful in future studies designed 
to understand better the interrelationships 
in this complex. 

ACKNOWLEDGEMENTS 
The writer expresses thanks to Dr. 
Henry van der Schalle, MoUusk Division, 
Museum of Zoology, University of Mich- 
igan, He suggested that this fresh-water 
mussel species complex might be suitable 
for a clinal demonstration and placed the 
collections of the MoUusk Division at the 
writer's disposal. 

REFERENCES 

BALL, G. H., 1922, Variation in Fresh- 
water mussels. Ecology, 3: 93-121» 

CLENCH, W. J., 1954, The occurrence 
of clines in molluscan populations (part 
of Symposium; subspecies and clines, 
99-126, 133). Syst. Zool., 3: 122-125. 

HUXLEY, J. S., 1938, Clines: an auxiliary 
taxonomic principle. Nature, 142: 219- 
220. 

M AYR, ERNST, 1942, Systematic s and 
origin of species. Columbia Univ. 
Press, New York. 334 p. 

ORTMANN, A. E., 1920, Correlation of 
shape and station in fresh-water 
mussels (naiades). Proc» Amer. Philos. 
Soc, 59: 268-312. 

VAN DER SCHALIE, HENRY, 1948, The 
land and fresh-water moUusks of Puerto 
Rico. Misc. Publ. Univ. Mich. Mus. 
Zool., No. 70. 134 p. 



ZUSAMMENFASSUNG 

GEFÄLLE IN DER MUSCHELGATTUNG LAMPSILIS (PELECYPODA: UNIONffiAE) 

Es wurde versucht ein geographisches Nord-Süd Gefälle in der Süsswassermuschel 
Lampsilis dadurch nachzuweisen, dass Schalenmessungen an 3 Arten dieser Gattung auf 
deren Vorkommen in verschiedenen Breitegraden bezogen und graphisch dargestellt 
wurden. Die 260 Exemplare auf denen diese Studie beruht stammen aus einem Gebiet, 
dass sich vom nördlichen Michigan bis ins südliche Alabama erstreckt; es handelt sich 
um L. ventricosa (Barnes) (121 Exemplare), L. ovata (Say) (79 Exemplare) und L. 
excavata (Lea) (60 Exemplare). Die angewandten Verhältniszahlen betreffen folgenae 
Masse der Schale: Höhe/Gesamtlänge, Breite/Gesamtlänge und Hintere Länge/Gesamt- 
länge. Die eingetragenen zerstreuten Punkte neigen zur Verdichtung auf der einen oder 
anderen Seite des Diagrammes, je nachdem um welche Messungen es sich handelt. Die 
Werte der Verhältniszahlen von Höhe und Breite zur Gesamtlänge steigen, je südlicher 
die Fundorte der Muscheln gelegen sind, während sie für diejenigen der hinteren Länge 



224 A. M. CVANCARA 

zur Gesamtlänge nach dem Süden hin fallen. Für das Bestehen eines Gefälles spricht, 
dass die Verbreitungsgebiete der 3 Arten sich überschneiden; dies trifft für die beiden 
nördlichen Arten L. ventricosa und L. ovata zu, und auch für die südliche Art L. 
excávala, deren Verbreitungsgebiet in dasjenige von L. ovata übergeht. Ob ein solches 
Gefälle nun besteht oder nicht, liess sich mittels der statistischen Analyse nicht 
eindeutig beweisen. Dennoch liegt es nahe, dass diese 3 nominellen Arten nur Unter- 
arten sind. Ein endgültiges Urteil wird jedoch nur auf Grund weiterer Studien über 
die Anatomie der Weichteile und die wechselseitige Fruchtbarkeit gefällt werden 
können. 



RESUME 

«CLINE» DE TROIS ESPECES DE LAMPSILIS (PELECYPODA: UNIONIDAE) 

Nous avons essayé de mettre en évidence un "cline" géographique nord-sud pour 3 
espèces de Lampsilis, en mettant en rapport les latitudes de leurs lieux de provenance 
et les proportions de leurs coquilles. Ces rapports ont été représentés graphiquement. 
Les 260 specimens utilisés dans cette étude appartiennent aux espèces L. ventricosa 
(Barnes) (121 specimens), L. ovata (Say) (79 specimens) et L. excavata (Lea) (60 speci- 
mens) et proviennent d'un territoire allant du Nord du Michigan jusqu'au sud de 
l'Alabama. Les rapports hauteur/longueur totale, largeur/hauteur totale et longueur 
postérieure/longueur totale furent mis en face des positions latitudinales. La dispersion 
des points des diagrammes, montre une tendance graduelle vers un côté ou l'autre, selon 
les mesures considérées: pour ceux qui concernent les rapports de la hauteur et de la 
largeur à la longueur totale, l'on distingue une augmentation des valeurs en allant vers 
le sud, tandis que pour les rapports de la longueur postérieure à la longueur totale, 
les valeurs calculées diminuent en allant vers le sud. Le fait que les aires de réparti- 
tion de ces 3 espèces se chevauchent donne prise à la suppesition de l'existence de ce 
"cline": c'est le cas pour les 2 espèces septentrionales, L. ventricosa et L. ovata et 
également pour l'espèce méridionale L. excavata dont l'aire se confond avec celle 
de L. ovata . Quoique l'analyse statistique ne nous ait pas permis de décider défini- 
tivement pour ou contre l'existence de ce "cline", il existe probablement et il se pour- 
rait bien que ces 3 espèces ne soient que des sous-espèces. Un jugement définitif ne 
sera possible qu'après confirmation par des études supplémentaires sur la morphologie 
des parties molles et sur Г interfertilité de ces espèces. 



RESUMEN 

CLING EN TRES ESPECIES DE LAMPSILIS (PELECYPODA: UNIONIDAE) 

Se utilizaron en este estudio 121 ejemplares áe Lamps His ventricosa (Barnes), 79 de 
L. ovata (Say) y 60 de L. excavata (Lea). Esas tres especies se distribuyen desde el 
norte de Michigan hasta el sur de Alabama. Se señalaron, en diagramas de correlación, 
tres medidas proporcionales de la concha - las razones entre altura/longitud total, 
diámetro/longitud total y longitud posterior/longitud total - en oposición a la situación 
latitudinal de los ejemplares de cada especie. Se observó una tendencia a la dis- 
locación gradual de los puntos para un u otro lado del diagrama, de conformidad con la 
razón utilizada. Así, en la dirección de las bajas latitudes aumenta la frecuencia de 
las razones altura/longitud total y diámetro/longitud total, y disminuye la frecuencia 
de la razón longitud posterior/longitud total. Las especies de más al norte, L. ventri- 
cosa y L. ovata, se sobreponen en sus respectivas distribuciones, y la distribución 
de.L. ovata se continúa con aquella de la especie del sur, L. excavata. Estas relaciones 
espaciales entre las tres especies favorecen la hipótesis de un clino geográfico de norte 
a sur. Sin embargo, el análisis estadístico de los datos ofrece poco para probar o negar 
esa hipótesis. El concepto de clino implicará en un cambio en la taxonomía de las 
tres especies nominales consideradas. Se sugiere que ellas son probablemente sub- 
especies. Un juicio definitivo depende de estudios confirmatorios basados en la morfo- 
logía de las partes blandas y en experimentos sobre la fertilidad de los cruzamientos. 



CLINES IN LAMPSILIS 225 

АБСТРАКТ 
КЛИНАЛИ В ТРЕХ ВИДАХ РОДА LAMPSILIS (BIVALVIA, UNIONmAE) 

Алан Кванкара 

Сравнивая широтный ареал трех пресноводных перловиц с измерениями их 
раковин, попытка сделана показать их клинали с севера на юг. Экземпляры 
были взяты для изучения их ареала от северного края озера Мичиган и на юг 
до южной Алабамы. Три измерения раковины в пропорции: вышина ко всей дли- 
не; ширина ко всей длине и задняя часть раковины ко всей длине ее были 
занесены на графу в соответствии с широтным ареалом каждого из трех видов: 
Lampsilis ventricosa (Barnes) - (121 экземпляр), L. ovata (Say) - (79 эк- 
земпляров) и L. excavata (Lea) - (60 экземпляров). Разбросанность точек 
диаграммы показывает тенденцию постепенного их сползания то в одну сторону, 
то в другую, в зависимости от того, какой пропорцией мы пользовались. 
Диаграммы пропорции раковины - высота ко всей длине и ширина ко всей дли- 
не - показывают увеличение, когда измерения относятся к экземплярам ниж- 
них широт. Пропорции же задней части раковины ко всей длине уменьшаются в 
экземплярах с нижних широт. Некоторое подтверждение клинали дает то обсто- 
ятельство, что ареалы всех трех видов перекрываются и почти совпадают. Бо- 
лее северные виды L. ventricosa и L. ovata сливаются своими ареалами и L. 
ovata в своих южных границах совпадает с ареалом L, excavata Статистичес- 
кий анализ имеющихся данных не достаточен для подтверждения или отрицания 
наличия клиналей. Указание на возможность наличия клинали заставляет под- 
нять вопрос таксономического характера трех указанных видов: возможно, что 
это только подвиды. Окончательное заключение об этом зависит от изучения 
их анатомии и экспериментов скрещивания . 



MUSSEL DISTRIBUTION IN RELATION TO FORMER STREAM CONFLUENCE 
IN NORTHERN MICHIGAN, U. S. A. 

by 

Henry van der Schalie 

Museum of Zoology, University of Michigan 

Ann Arbor, Michigan, U. S. A. 

ABSTRACT 

It has been shown previously that certain Mississippi River naiades have invaded the 
St. Lawrence drainage system in the region of the Fox River and Green Bay on the 
western shore of Lake Michigan, Wisconsin, in post-glacial times when the Fox River 
was still joined to the Wisconsin River, a tributary of the Mississippi. The fluviatile 
species Alasmidonta marginata and Actinonaias carinata, for instance, now occur in 
3 streams flowing into Green Bay, but not in the impounded waters of the Lake tself. 
The present discontinuous distribution of these mussels was explained by a former en- 
larged Fox River system with a dendritic river pattern that comprized these rivers 
during a low water stage of Lake Michigan. 

The southern species Alasmidonta marginata, Elliptio dilatatus ama Lasmigona costata 
have been found in 3 northern Michigan rivers: the Millecoquin, in the eastern part of 
the Upper Peninsula, and the Carp and Ocqueoc, in the northern part of the Lower Pen- 
insula. Again we have a discontinuous pattern of distribution. Particularly A. marginata 
is strictly fluviatile and the 2 other species also do not occur in Lake Michigan. Such 
an extension of their range from the northwest can be accounted for best by geomorpho- 
logical evidence. Glacial geologists have indicated that a former Mackinac River occu- 
pied the bed of northern Lake Michigan during a post-glacial low water stage in 
Chippewa -Stanley times, approximately 8500 years ago. The rivers concerned, now 
tributaries of Lake Michigan and Lake Huron, must have been connected with the now 
submerged Mackinac River system before the higher lake levels separated them. 

An Atlantic species, Elliptio complanatus, has reached northern Michigan through 
other post-glacial confluences, for the east. It has also been found in the Ocqueoc River, 
although it is known to be absent from the Lower Peninsula, and in the Millecoquin of the 
Upper peninsula. 



The relations of the distribution of 
fresh-water mussels to geomorphology 
have been discussed in several earlier 
accounts. Although this subject has been 
somewhat controversial, facts to indicate 
that mussel distribution does serve as a 
means for determining post-glacial 
stream confluence have been demonstrated 
in several regions. For the Great Lake 
region of the Northern United States of 
America, which was formerly glaciated, 
the sequence of events that occurred in 
post-glacial history, as revealed by glacial 
geologists such as Leverett and Taylor 
(1915), Stanley (1938), Hough (1955, 1958) 
and others, can best explain certain 
features of present naiad distribution. 

Broadly speaking, it is apparent that 
some species typical for the Mississippi 
drainage, a system draining southwards 



since glacial times, are also present in 
the upper reaches of the more recent Great 
Lakes - St. Lawrence hydrographical 
system, which drains to the east and which 
has captured some of the headwaters of 
the Mississippi system. The present di- 
vides lie in northeastern Wisconsin and 
in northern Illinois and Indiana and the 
whole of Michigan belongs to the St. 
Lawrence watershed. 

Particulars on naiad distribution in this 
area and on its correlation with glacial 
history are found in the literature. Good- 
rich and van der Schalie (1939: 40) have 
shown that certain Mississippi naiades 
entered rivers tributary to the Green Bay 
of Lake Michigan, Wisconsin, at a low 
water stage of the Lake during which there 
existed an enlarged Fox River System with 
a dendritic river pattern. Since these 



(227) 



228 



H. VAN DER SCHAUE 



species are, in part, strictly fluviatile, or 
at least do not inhabit Lake Michigan, such 
a fromerly connected river system ap- 
pears to be an essential factor in ac- 
counting for the present occurrence of 
these species in streams that are now 
discontinuous due to the present higher 
water level in Green Bay. Further perti- 
nent data are given, for northeastern Wis- 
consin and northwestern Michigan, by 
Walker (1913), H. B. Baker (1922), Morri- 
son (1932) and van der Schalle (1939, 1945); 
for southwestern Michigan, by van der 
Schalle (1941, 1945) and, for southeastern 
Michigan, by Walker (1913), Ortmann 
(1924) and van der Schalle (1939). In 
central New York, Clarke and Berg (1959) 
have more recently correlated mussel 
distribution with geologic history. 

With additional information now availa- 
ble, it is possible to show that the influx 
of the southern Mississippi mussel fauna 
into the Northern Peninsula of Michigan 
extended a considerable distance north- 
eastward beyond the Green Bay area than 
previously known, as far east as, and even 
beyond the Mackinac Straits between Lakes 
Michigan and Huron. The studies on the 
rivers of the Great Lakes, as published by 
Stanley (1938) and Hough (1958) are here 
shown to account for this influx. 

In view of past misunderstanding as to 
the value of mussel distribution as an aid 
in determining stream confluence, it must 
again be emphasized that fresh-water 
mussels are an especially useful group 
for relating their patterns of distribution 
to both the present and the past history 
of the streams in which they now live» 
The controversial aspects of the subject 
have been discussed by Ortmann (1913) 
and van der Schalle (1939, 1945). Passive 
means of distribution, other than fishes on 
which the animals are normally parasites, 
do not serve to account for the patterns in 
distribution now observed. Most attempts 
to explain mussel dispersion by birds as 
passive agents are based on untenable bi- 
ological conditions and do not serve either 
to explain the definite inter-relation of 
mussels with their environmental con- 
ditions or the intricate relations necessary 



for the successful completion of the life 
histories that mussels must have with 
their fish hosts. 

Knowledge of the mussel fauna in the 
streams of the Upper Peninsula of Mich- 
igan is all too incomplete. There are 
several reasons for a lack of such data. The 
area is still a rather extensive wasteland, 
with very few roads providing access to 
its streams. Many of the rivers are not 
favorable for mussels throughout their 
entire course because the bottom often 
tends to be too sandy; mussels do not main- 
tain themselves on shoals with shifting 
sands. It thus becomes very difficult to 
determine which species live in a particu- 
lar drainage system, since an accessible 
stretch of a stream bottom may be un- 
productive while not far away in the same 
stream mussels thrive on a firm bottom. 
With these conditions in mind, it is obvious 
that one cannot be certain that the infor- 
mation available is anything but fragment- 
ary. However, the few reliable data 
available, already do enable one to postu- 
late the conditions that must have existed 
during the late Pleistocene, when lakes 
and rivers were connected in such a way 
as to permit the patterns of distributions 
now observed among some of the mussels 
in northern Michigan. It should be stressed 
that information of this kind ought to be 
obtained before the rivers are subjected 
to detrimental human influences that may 
eradicate the original fauna. 

While 8 species are involved in showing 
stream confluence in northern Michigan 
and Wisconsin, the distribution patterns 
of 2 river-inhabiting species, Actinona- 
ias carinata Bsivnes Sind Alas midonta mar- 
ginata Say, have already been stressed 
by Goodrich and van der Schalle (1939: 
41-44, Map 2). They occur in north- 
eastern Wisconsin, in the Oconto, Peshtigo 
and Menominee rivers (Fig. 1), but are 
unable to maintain themselves in im- 
pounded waters such as Green Bay and 
Lake Michigan itself. These species, now, 
occurring in 3 separate streams, clearly 
have a discontinuous distribution pattern. 
For a previous continuous river pattern 
that would explain this distribution, a 



MUSSEL DISTRIBUTION AND STREAM CONFLUENCE 



229 




230 



H. VAN DER SCHALIE 



low -water stage must have existed in 
Green Bay and Lake Michigan in former 
times. In fact, during the post-Algon- 
quin period, the streams in Wisconsin and 
northwestern Michigan, now draining into 
the lake, connected with the enlarged Fox 
River, then flowing through the bed of 
Green Bay, to form a continuous dendritic 
pattern. These former confluences have 
been indicated in that previous account. 
The Mackinac River drainage . Recent 
studies by Hough (1955, 1958) using radio- 
carbon dating techniques confirm this low- 
water stage in post -Algonquin and pre- 
Nipissing time; Hough places the water 
level as much as 350 feet belov/ the present 
lake surface. More recently Hough (1963) 
clearly summarizes the glacial lake levels 
as they occurred in succession in the Lake 
Huron basin. His Fig. 7 shows the time 
sequences of the several lake stages in 
relation to sea level. He indicates that the 
Algonquin stage, with anageof 11,000B.P. 
(Before Present) and at an altitude of 605 
feet above sea level, was followed by a 
large drop in level (about 370 feet) in the 
Stanley stage to a low level of 190 feet 
above sea level. This was followed by a 
gradual rise so that about 4500 years later 
the Nipissing stage was attained (about 
4500 B.P.) when the water level was again 
605 feet above sea level. In earlier ac- 
counts the low level of lake water was 
simply referred to as the "Algonquin- 
Nipissing" stage. These newer data pro- 
vide a useful tool for studies of stream con- 
fluence. 

Hough's studies and those by Stanley 
(1938) also show that a submerged Macki- 
nac River channel (Fig. 1.) existed in 
northern Lake Michigan. Three additional 
river connections in that area can now be 
indicated to account for the presence in 
recent time of 3 Mississippi naiades, the 
river - inhabiting species, Alasmidonta 
marginata Say, and 2 other species not 
found in Lake Michigan, Elliptio dilatatus 
(Rafinesque) and Lasmigona costata 
(Rafinesque). The 3 rivers in which this 
southern, Mississippi River faunal group 
has been found are the Millecoquin River 
in the Upper Peninsula of Michigan and 



the Carp and Ocqueoc Rivers in the Lower 
Peninsula (Fig. 1). Another, Atlantic 
species, Elliptio complanatus (Dillwyn), 
was also found in 2 of these streams» 
Former confluences must have existed to 
account for the presence of such faunal 
elements in the northern Michigan 
streams, which evidently once were part 
of a Mackinac River drainage. It is with 
the evidence of these confluences that we 
can now understand how the southern 
mussels could be established farther north 
and east than hitherto suspected. Each of 
the 3 drainages will be considered sepa- 
rately. 

The Millecoquin River . On August 23, 
1941, Dr. Carl L. Hubbs collected three 
species of fresh-water mussels from that 
River» Among the eight specimens col- 
lected were three Alasmidonta marginata 
Say, an location even farther to the north- 
east than the Wisconsin-Michigan border 
and also far from its normal southern 
range in the Lower Peninsula of Michigan. 
Because this discovery was so unusual the 
Millecoquin River was re-visited on Oc- 
tober 4 of the same year. During this 
survey the following species were col- 
lected: 

Unioninae: 

Elliptio complanatus (Dillwyn) 
*Elliptio dilatatus (Rafinesque) 

Anodontinae: 

Anodonta grandis Say 

Anodontoides ferussacianus (Lea) 
*Lasmigona costata (Rafinesque) 
*Alasmidonta marginata Say 

Lampsilinae: 

Lampsilis siliquoidea (Barnes) 
Lampsilis ventricosa (Barnes) 

The three species marked with asterisks 
in the above list are characteristically 
among the Mississippi fauna (van der 
Schalle, 1939: 39-45), and they indicate 
former conditions not now present in the 
Great Lakes. While Elliptio dilatatus and 
Lasmigona costata have not been reported 
(Goodrich and van der Schalle, 1932) from 



MUSSEL DISTRIBUTION AND STREAM CONFLUENCE 



231 



Lake Michigan, both species are known to 
be able to live in a lake environment (van 
der Schalle, 1938), particularly if the lake 
has a stream influence as brought about by 
a strong inlet or outlet, or both. Since 
Lake Michigan does not support a rich 
mussel fauna, both species actually have a 
discontinuous pattern; they probably 
reached the Millecoquin with Alasmidonta 
marginata during a period of stream con- 
fluence. 

The presence of Elliptio complanatus 
(Dillwyn) in the Upper Peninsula clearly 
indicates an invasion through confluence 
from the east, since this species belongs 
to the North Atlantic (St. Lawrence River) 
mussel assemblage (van der Schalle, 1950: 
449-450). The species probably traveled 
westward as glochidia attached to fish, 
from Quebec through the Trent andNipis- 
sing outlets into Georgian Bay, from there 
to spread, according to Walker (1913:45), 
"along the north shore of Georgian Bay 
[of Lake Huron] into the St. Mary's [River], 
and from thence into the eastern Lake Su- 
perior, without getting either into Lake 
Erie, Lake St. Clair, or the lower part of 
Lake Huron". With regard to the period 
of this spread, Clarke and Berg (1959) 
indicated that the Trent Outlet stage was 
more likely than the Nipissing outlet stage 
(which is the present valley of the Ottawa 
River). 

Carp River . This stream in the upper 
part of the Lower Peninsula flows north- 
wards into northern Lake Michigan (Fig. 
1), and there is one authentic record in 
the collections of the Museum of Zoology, 
University of Michigan, to establish that 
Alasmidonta marginata has been found in 
this stream. Royal Brunson collected this 
species on July 20, 1945, at the mouth of 
Carp River, Emmet County (UMMZ 
197969). The predominantly southern dis- 
tribution of Alasmidonta marginata in 
Michigan has been recognized for more 
than half a centry and is thus indicated by 
Bryant Walker (1898: 6) when he stated 
"Margaritina marginata Say [now known as 
Alasmidonta marginata] is apparently of 
general distribution through the southern 
part of the state [Michigan] and has been 



found as far north as Houghton Lake, 
Roscommon county, the source of the 
Muskegon river". This location is about 
170 miles up Michigan's Lower Peninsula, 
a region accessible to Mississippi mussels 
from the south, through the Des Plaines- 
lUinois and the Maumee routes, which 
were formerly connected with the Missis- 
sippi drainage. 

The Ocqueoc River drainage . This 
lower Peninsula stream also flows to the 
north and drains into Lake Huron at Ham- 
mond Bay (Fig. 1). The following mussels, 
collected in 1948 by Harold W. Harry and 
me, represent the recent mussel fauna in 
Ocqueoc River: 

Unioninae: 

*ElUptio com.planatus (Dillwyn) 

Anodontinae: 

Anodonta grandis Say 

Alasmidonta calecolus (Lea) 
*Alasmidonta marginata Say 

Lasmigona compressa (Lea) 
*Lasmigona costata (Rafinesque) 

Strophitus rugosus (Swainson) 

Lampilinae: 

Lampsilis siliquoidea (Barnes) 

The species marked with an asterisk are 
of special interest in that they would not 
be anticipated as a part of the fauna of the 
river in this area while the 5 other species 
are normally found in northern rivers such 
as the Ocqueoc. These species have used 
two separate avenues of invasion, the 
Elliptio complanatus reaching the Ocqueoc 
from the east, while Alasmidonta margin- 
ata and Lasmigona costata definitely came 
from the northwest. 

The mussels of the Ocqueoc drainage 
have long been known to represent an un- 
usual assemblage in which northern and 
southern elements are found intermingling 
with remarkable discontinuity among 
several faunal elements. The disparity 
can now be explained best in terms of the 
submerged Mackinac River channel, 
backed by means of additional evidence 
adduced by Stanley (1938) and by Hough 



232 



H. VAN DER SCHALIE 



(1955, 1958), which shows that there was 
a low-water stage known as "Lake Stan- 
ley" in the Huron basin. Hough (1955: 
967) stated: «Detailed study of the present 
lake -bottom topography should reveal 
many more effects of low stages of the 
lake. Captain Vernon Seaman of the re- 
search vessel Cisco reports (Personal 
communication, 1951) that fishermenhave 
brought up in their nets, from a depth of 85 
feet, off Hammond Bay, Lake Huron, whole 
trees complete with their roots and bearing 
no man-made scars. These trees, perhaps 
from a flooded forest, were identified as 
Tamaracks". This information tends to 
strengthen the belief that a level suf- 
ficiently low must have existed to permit 
the river confluence necessary for the 
introduction of the river species Alasmi- 
donta marginata into the Ocqueoc drainage 
from the northwest; this low level could 
account for the interesting pattern ob- 
served in the distribution oiElliptio com- 
planatus. The time when this low-water 
stage occurred has been established as 
7850 ± 350, according to radiocarbon 
dates assigned by Crane and Griffin (1960: 
31) for vegetable matter from Grand 
Traverse Bay; the radiocarbon age of wood 
from two stumps in situ in Thompson's 
Harbor in Lake Huron was 7250 ± 300 
years (1961: 106). Farrand (unpublished 
thesis, 1960) places the beginning of the 
Chippewa-Stanley period at 8500 years 
ago which is some 2000 years earlier 
than the date estimated by Hough (1958). 
The occurrence of Elliptio complanatus 
in the Ocqueoc drainage has been known 
for many years. Why it lived nowhere 
else in the southern peninsula has been 
a matter open to conjecture. The records 
(Walker, 1898: 11; Matte son, 1948: 14) for 
its occurrence in Macomb, Lenawee and 
Monroe counties are dubious and uncon- 
firmed, since many years of collecting 
have shown that this species is not a normal 
inhabitant in the southern regions. Its pre- 
valence in the Ocqueoc and its absence as 
a regular element in the fauna of all 
streams in the remainder of the lower 
Michigan Peninsula have been well au- 
thenticated and can be adequately sub- 



stantiated by the hundreds of distribution 
records available in the Museum of Zoo- 
logy at the University of Michigan. Mat- 
teson (1948: 13, Fig. 1) used those records 
to show distribution in Michigan; his map 
clearly indicates its isolated occurrence 
in the Ocqueoc region. Ortmann (1924: 
116) suggested that the few scattered out- 
lying records of Elliptio complanatus in- 
dicated that it might be expanding its 
range southward at the present time. 
However, this extension has not been ob- 
served to have taken place. 

The faunal list for the Ocqueoc River 
does not include Elliptio dilatatus (Raf- 
inesque) although the Museum of Zoology 
collections record it from some of the 
other rivers in the northern part of the 
southern Peninsula such as: the Devil 
River and Thunder Bay River in Alpena 
County; the Rifle River in Ogemaw County; 
Sylvan and Crystal lakes in Leelanau 
County; Platte River, Benzie County; and 
Betsie Creek, Grand Traverse County. 
It would be interesting to discern the 
reasons for its absence in the Ocqueoc 
and its presence in the Carp and Mille- 
coquin rivers. 

Alasmidonta marginata and Lasmigona 
costata are both well established in the 
Ocqueoc drainage. While the former has 
not been recorded farther east along this 
northern route, there is evidence that Las- 
migona costata, clearly a Mississippi 
species, did travel far to the east with 
records for the Erie Canal in New York 
(Clarke and Berg, 1959: 8-9) and the Rideau 
River at Ottawa, Ontario (LaRocque and 
Oughton, 1937: 152-53). This species 
seems to have migrated both through the 
southern Greater Maumee system (in the 
basin of present Lake Erie) and the former 
Mackinac River, in the north, to establish 
itself far in the St. Lawrence drainage 
system, 

REFERENCES 

BAKER, H. В., 1922, The Mollusca of 
Dickinson County, Michigan. Occ. Pap. 
Mus. Zool., Univ. Mich., HI: 1-44, 
1 map. 



MUSSEL DISTRIBUTION AND STREAM CONFLUENCE 



233 



CLARKE, A. J., Jr. and BERG, C. O., 

1959, The Freshwater Mussels of 

Central New York. Cornell Univ., 

Memoir 367: 1-79. 
CRANE, H. R. and GRIFFIN, J. В., 1960, 

University of Michigan radiocarbon 

dates V. Amer. J. Sei. Radiocarb. 

Suppl., 2: 31-48. 
, 1961, University of Michigan 

radiocarbon dates VI. Amer. J. Sei. 

Radiocarb. Suppl., 3: 105-125. 
FARRAND, William R., 1960, Former 

shorelines in western and northern Lake 

Superior basin. Unpubl. Ph.D. Thesis^, 

Univ. Mich., 1-lv, 226 p. 
GOODRICH, Calvin and VAN DER 

SCHALIE, Henry, 1932, II. The naiad 

species of the Great Lakes. Occ. Pap. 

Mus. Zool., Univ. Mich., 238: 8-14. 
, 1939, Aquatic mollusks of the 

Upper Peninsula of Michigan. Misc. 

Pub. Mus. Zool., Univ. Mich., 43: 1-45. 
HOUGH, Jack L., 1955, Lake Chippewa, 

a low stage of Lake Michigan indicated 

by bottom sediments. Bull. Geol. Soc. 

Amer., 66: 957-968. 
, 1958, Geology of the Great 

Lakes. Univ. Illinois Press, Urbana, 

i-xviii, 1-313. 
, 1963, The Prehistoric Great 



Lakes of North America. Amer. Sei., 

51: 84-109. 
LaROCQUE, Aurèle and OUGHTON, J., 

1937, A preliminary account of the 

Unionidae of Ontario. Canad. J. Res. 

D, 15: 147-155. 
LEVERETT, Frank and TAYLOR, F. В., 

1915, The Pleistocene of Indiana and 

Michigan and the history of the Great 

Lakes. U. S. Geol. Surv. Monogr., 53: 

1-529, pi. 1-32. 
MATTESON, MaxR., 1948, Thetaxonomic 

and distributional history of the fresh- 



water m\xsséi Elliptio complanatus {Dil- 
Iwyn, 1817). Nautilus, 61: 127-132; 62: 
13-17. 

MORRISON, J. P. E., 1932, A report on 
the Mollusca of the northeastern Wis- 
consion lake district. Trans. Wise. 
Acad. Sei., Arts and Letters, 27:359-96. 

ORTMANN, A. E., 1913, The AUeghenian 
divide, and its influence upon the fresh- 
water fauna. Proc. Amer» Philos. Soc., 
52: 287-390, pi. 12-14. 

, 1924, Distributional features of 

naiades in tributaries of Lake Erie. 
Amer. Midi. Nat., 9: 101-117. 

STANLEY, George, 1938, The submerged 
valley through Mackinac Straits. J. 
Geol. 46: 966-74. 

VAN DER SCHALIE, Henry, 1938, The 
naiad fauna of the Huron River in south- 
eastern Michigan. Misc. Pap. Mus, 
ZooL, Univ. of Mich., 40: 1-83. 

, 1939, Distributional studies 

of the naiades as related to geomor- 
phology. J. Geomorph., 2: 251-257. 

, 1941, Zoogeography of naiades 



in the Grand and Muskegon rivers of 
Michigan as related to glacial history. 
Pap. Mich. Acad. Sei., Arts and Letters, 
26: 297-310. 
, 1945, The value of mussel 



distribution in tracing stream conflu- 
ence. Pap. Mich. Acad. Sei., Arts and 
Letters, 30: 355-373. 

VAN DER SCHALIE, Henry and Annette, 
1950, The mussels of the Mississippi 
River. Amer. Midi. Nat., 44: 448-66. 

WALKER, Bryant, 1898, The distribution 
of the Unionidae in Michigan. Detroit: 
privately printed by the author, 23 p. 
PI. 1-3. 

, 1913, The Unione fauna of the 

Great Lakes. Nautilus, 27: 18-23; 29- 
34; 40-47; 56-59. 



^Obtainable through University Microfilms Inc., Ann Arbor, Mich. 



234 H. VAN DER SCHALIE 

ZUSAMMENFASSUNG 

DER EINFLUSS EHEMALIGER FLUSSVERBINDUNGEN AUF DIE 
VERBREITUNG EINIGER MUSCHELN Ш NÖRDLICHEN MICHIGAN, V. S, A. 

Ich habe schon früher darauf hingewiesen, dass gewisse Naiaden des Mississippi- 
flusses das St. Lorenz Entwässerungsbecken nach der Eiszeit in der Nähe des Fox- 
flusses und der Green-Bucht, am westlichen Ufer des Michigansees, in Wisconsin, 
besiedelt haben, zu einer Zeit als der Foxfluss noch mit dem Wisconsinfluss, einem 
Nebenfluss des Mississippi, in Verbindung stand. Z.B. kommen die Flussmuscheln 
Actinonaias carinata und Alasmidonta marginata jetzt in 3 verschiedenen Neben- 
flüssen der "Green Bay", nicht aber in den Stauwässern des Sees selbst vor. Die 
gegenwärtige diskontinuierliche Verbreitung dieser Arten habe ich im Zusammenhang 
damit erklärt, dass der Foxfluss während einer liefwasserperiode des Michigansees 
ein ausgedehnteres, verzweigtes System bildete, dem diese Flüsse angenörten. 

Die südlichen Muscheln Alasmidonta marginata, Elliptio dilatatus und Lasmigona 
costata wurden nun auch in 3 Flüssen des nördlichen Micnigan gefunden: im Millecoquin, 
der im östlichen Teil der Oberen Halbinsel gelegen ist, und in den Carp und Ocqueoc 
Flüssen, die im nördlichen Teil der Unteren Halbinsel liegen, wobei zu beachten ist, 
dass insbesondre A. marginata eine ausgesprochen fluviatile Art ist und die beiden 
anderen Arten zumindest im See nicht angetroffen werden. Diese Funde zeigen, dass 
es den Mississippiarten gelungen ist, vom Nordwesten her bedeutend weiter in das 
St. Lorenz Abzugsbecken einzudringen als bisher angenommen wurde. Wieder sehen 
wir ein zersplittertes Verbreitungsbild, das am besten durch die inzwischen bekannt 
gewordene geologische Vorgeschichte der Gegend erklärt werden kann. Während einer 
post-glazialen Tiefwasserperiode in der Chippewa-Stanley Zeit, vor ungefähr 8500 
Jahren, durchströmte ein ehemaliger Mackinacfluss das Bett des nördlichen Michigan- 
sees. Die erwähnten Flüsse, welche sich jetzt in die Michigan- und Huronseen ergiessen, 
gehörten zweifelsohne dem Mackinacsystem an, bevor die höheren Wasserspiegel in den 
Seen ihre Verbindung unterbrachen. 

Andrerseits gelangte eine atlantische Art, Elliptio complanatus, vom Osten her 
durch andere ehemalige Flussverbindungen ins nördliche Michigan. Diese Art wurde 
ebenfalls im Ocqueocfluss gefunden, obwohl sie bekanntermassen sonst in der südlichen 
Halbinsel fehlt, und auch im Millecoquin der nördlichen Halbinsel. 

RESUME 

L'INFLUENCE DE JONCTIONS FLUVIÁTILES DU PASSÉ, SUR LA DISTRIBUTION DE 
CERTAINES NAIADES DANS LE NORD DU MICHIGAN, E. U. A, 

Nous avons déjà montré que certaines espèces naiades fluviátiles du Mississippi ont 
envahi le bassin du St. Laurent dans la région du fleuve Fox et de la "Green Bay" sur 
la rive occidentale du lac Michigan, au Wisconsin, après la glaciation, pendant que le 
Fox était encore uni au fleuve Wisconsin, un affluent du Mississippi. Par exemple, 
on trouve à présent les espèces Actinonaias carinata et Alasmidonta marginata dans 
3 rivières tributaires de la baie Green mais pas dans les eaux du lac même. La 
présente discontinuité dans la distribution de ces bivalves a été expliquée par l'existence 
d'un système Fox plus important autrefois qu'aujourd'hui et à disposition dendritique, 
qui englobait les 3 rivières actuelles pendant une période d'eaux basses du Lac Michigan. 

Les espèces méridionales Alasmidonta marginata, Elliptio dilatatus et Lasmigona 
costata ont été trouvées dans 3 rivières du nord du Michigan: le Millecoquin, situé 
dans l'est de la Péninsule Supérieure, et le Carp et l'Ocquéoc, situes dans le nord de 
la Péninsule Inférieure. Nous avous donc là aussi une distribution discontinue. Notons 
que l'espèce A. marginata en particulier est strictement fluviatile et que les 2 autres 
espèces aussi font dé faut dans le lac Michigan. La grande extension qui n'est ainsi 
produite à partir du nord-ovest trouve sa meilleure explication dans l'histoire géo- 
morphologique de la région. Les géologues du glaciaire ont indiqué récemment divulgee. 
Qu'une ancienne rivière Mackinac occupait le lit du lac Michigan du nord pendant une 
période post-glaciaine d'eaux basses, au temps du Chippewa-Stanley, il-y-a environ 
8500 années. Sans doute les rivières en question, maintenant tributaires des lacs 
Michigan et Huron, faisaient-elles partie de l'ancien système Mackinac et étaient-elles 
alors en communication, avant que les niveaux plus élevés des lacs les séparent. 



MUSSEL DISTRIBUTION AND STREAM CONFLUENCE 235 

D'autre part une espèce atlantique, Elliptio complanatus , venant de l'est, a pénétré 
jusqu'au nord du Michigan par d'autres confluences du passé. L'espèce, dont on 
connaît l'absence de la Péninsule Inférieure en général, n'y a été trouvée que dans 
l'Ocquéoc; et, dans la Péninsule Supérieure, elle a été trouvée dans le Millecoquin. 

RESUMEN 

DISTRIBUCIÓN DE ALMEJAS EN RELACIÓN CON ANTIGUAS CONFLUENCIAS 
DE CORRIENTES EN EL NORTE DE MICHIGAN, U. S. A. 

Ha sido demostrado previamente que ciertas almejas del río Mississippi invadieron 
el sistema de drenaje del San Lorenzo en la región del río Fox y Bahia Green en la 
costa oeste del lago Michigan, Wisconsin, en tiempos post-glaciales, cuando el río 
Fox todavía estaba unido al Wisconsin, tributario del Mississippi. Las especies 
fluviales Alasmidonta marginata y Actinonaias carinata, por ejemplo, aparecen ahora 
en tres cursos que desembocan en Bahia Green, pero no en las aguas embalsadas del 
lago mismo. La presente distribución discontinua de estas almejas fué explicada por 
un antiguo sistema más amplio y de configuración dendrítica del río Fox, que englobaba 
esos ríos, durante un periodo de aguas bajas del lago Michigan. 

Las especies meridionales Alasmidonta marginata, Elliptio dilatatus y Lasm,igona 
costata se encontraron en 3 ríos del norte de Michigan: el Millecoquin en la parte 
este de la Alta Península, y en los ríos Carp y Ocqueoc en la parte norte de la Baja 
Península. Aquí, otra vez, tenemos un tipo de distribución discontinua. Particularmente 
A. marginata es estrictamente fluvial y las otras dos especies tampoco se encuentran 
en el lago Michigan, fal extensión de sus áreas desde el noroeste puede estimarse 
mejor por evidencias geomorfológicas. Los glaciólogos han indicado que un antiguo 
río Mackinac ocupaba el lecho del norte del lago Michigan durante una fase post- 
glacial de aguas bajas en la época Chippewa-Stanley, hace aproximadamente 8.500 años. 
Los ríos en cuestión, hoy tributarios de los lagos Michigan y Huron, deben haber estado 
conectados con el sistema del río Mackinac, sumergido al presente, antes que el alto 
nivel de las aguas lacustres los separaran. 

Una especie del drenaje atlántico, Elliptio complanatus, alcanzó el norte de Michigan 
desde el este, a través de otras confluencias post-glaciales. Ha sido encontrada 
también en el río Ocqueoc, aunque se sabe que está ausente en la Baja Península, y 
en el Millecoquin de la Alta Península. 

АБСТРАКТ 

РАСПРОСТРАНЕНИЕ ЖЕМЧУЖНИЦ В СВЯЗИ С ПРЕЖНИМ СЛИЯНИЕМ ПРИТОКОВ НА СЕВЕРЕ 

ОЗЕРА МИЧИГАН, С.Ш.А. 

Генри Ван Дэр Шалэ 

Ранее было показано, что некоторые виды наяд реки Миссиссиппи вторг - 
лись в бассейн реки Сэйнт Лорэнс в районе реки Фокс и Грин Бэй с западной 
стороны озера Мичиган, в штате Висконсин, в послеледниковое время, когда 
река Фокс была еще соединена с рекой Висконсин, притоком реки Миссиссиппи. 
Речные виды Alasmidonta marginata и Actinonaias carinata, например, сегод- 
ня живут в трех ручьях, впадающих в Грин Бэй, но не в водах самого озера. 
Настоящая оторванность ареала этих моллюсков объясняется прежним расшире- 
нием бассейна реки Фокс с ее разветвлениями, которые образуют три реки во 
время половодья в озере Мичиган. 

Южные виды Alasmidonta marginata, Elliptio dilatatus и Lasmigona 
costata в трех северных реках штата Мичиган: в Миллекокин, в восточной 
части Верхнего Полуострова и в Карп и Оквэок, в северной части Нижнего 
Полуострова. Тут снова мы находим перерыв в ареале распространения. 
В частности, А. marginata -строго речной моллюск и два других вида также 
не живут в озере Мичиган. Такое удлинение их ареала от северозапада может 
служить лучшим геоморфологическим показателем. Геологи-ледниковеды указы- 
вали на тот факт, что прежняя река Макинак занимала ложе северной части 
озера Мичиган в пост-ледниковый период мелководья в эпоху Чиппива-Стаг1леи, 
приблизительно 8500 лет тому назад. Реки, о которых идет речь, в настоящее 
время служащие притоками озера Мичиган и озера Хурон, должны были быть со- 
единенными с, ныне погруженным бассейном реки Макинак, прежде чем более 



236 H. VAN DER SCHALIE 

высокие уровни озер разъединили их. 

Атлантический вид Elliptio complanatus достиг северного Мичигана че- 
рез другие пост-ледниковые слияния с востока. Он был также найден в реке 
Оквэок, хотя он и неизвестен в Нижнем Полуострове и в Миллэкокине Верхне- 
го Полуострова. 



FRESHWATER SNAILS OF THE SUBGENUS HINKLEYIA 
(LYMNAEIDAE: STAGNICOLA) FROM THE WESTERN UNITED STATES^ 

D. W. Taylor^, H. J. Walter^, and J. B. Burch4 

U. S. Geological Survey, Washington, D. C, U. S. A. 

The Liberian Institute 
The American Foundation For Tropical Medicine 
Harbel, Liberia 

Museum and Department of Zoology 

University of Michigan 

Ann Arbor, Michigan, U. S. A. 

ABSTRACT 



The subgenus Hinkleyia has heretofore included only Stagnicola caperata (Say), but is 
herein increased by addition of S. montanensis (Baker) on various conchological and 
anatomical criteria, and ofS. /)z7sbryz(Hemphill) on shell features only. New information 
permits a revised diagnosis of Hinkleyia, which has several distinctive characters but 
is worthy of only subgeneric rank. 

Sixteen specimens of a preserved series of S. montanensis irom Idaho were dissected. 
Anatomically they resemble S. caperata so closely that no distinguishing features could 
be identified. 

The two species can be distinguished by their shells. In shape, S. montanensis is 
usually more narrowly elongate and S. caperata. more swollen, but these characters 
overlap and surface texture and sculpture are the only consistently reliable criteria for 
distinction. Relatively conspicuous raised spiral ridges of periostraciun are diagnostic 
of S. caperata and a shiny surface without such sculpture but with spirally arranged 
series of tiny crescents of S. montanensis. 

The anatomical characters shared by these 2 species and typical American Stagnicola 
and, as far as is known, exclusive to them, are: a well-developed vaginal sphincter 
muscle; a large diverticulum appended to the proximal end of the upper prostate; a 
relatively stout and comparatively short penis sheath; a relatively short, bilaterally 
symmetrical penis having a muscular "knot" near its midlength; and a well-developed 
series of clearly bicuspid lateral radular teeth. 

In comparison with typical Stagnicola, Hinkleyia (i.e.,S. montanensis and S. caperata) 
shows a somewhat different and less prominent development of the vaginal sphincter, a 
notably stout vas deferens and a shorter penis that has a less prominent, somewhat more 
distally placed "knot*. Of special note is the tapered portion of the penis that is distal 
to the "knot", which is short and stout and much less distinctly demarcated from the 
thick proximal portion than in Stagnicola proper. Both species also have an imusually 



1 Contribution No. 1, Western American Freshwater Mollusks Program, Institute of Malacology. 

9 

Publication authorized by the Director, U. S. Geological Survey. 

3work supported by grant E-952, National Institute of Allergy and Infectious Diseases, U. S. Public Health 
Service. Present Address: Museum of Zoology, University of Michigan, Ann Arbor, Michigan, U. S. A. 

4work supported by grant 2E-41, National Institute of Allergy and Infectious Diseases, U. S. Public Health 
Service. 

(237) 



238 



TAYLOR, WALTER AND BURCH 



Short and thick penis sheath, a prostate of a particular conformation, and an uncommonly 
robust relative development of the lower part of the duct of the spermatheca. Addition- 
ally, in texture and pigmentation of their overall anatomy, they show similarities which, 
further serve to set them apart from other sufficiently known lymnaeid species. Their 
bodies are well pigmented and evidently their foot and tentacles are relatively slender 
in life. 

It was also found that S. montanensis had become sexually mature upon reaching a shell 
length of 6 to 7 mm. It is conjectured that the unknown egg mass of this species will 
prove to be similar to that of S. caperata, which among known masses is unique in the 
relative thickness of the individual egg envelopes and the thin inconspicuous outer tunic 
of the egg mass. 

Anatomical evidence indicates that a species formerly assigned to Stagnicola under 
the subgenus Nasonia is closely related to Fossaria and therefore not allied to S. 
montanensis and S. caperata. A possible special affinity of S. arcit'ca with Яг/г^/еум 
rather than the subgenus Stagnicola was considered but rejected on new anatomical data. 

The haploid chromosome numbers of S. montanensis and S. caperata are 18; the 
demonstrated diploid number of S. montanensisis36. These numbers are characteristic 
of basommatophoran snails in general. Details of gametogenesis, including the mono- 
centric nature of the chromosomes, seem to be the same as in other lymnaeids. During 
spermatogenesis there are normally 6 spermatogonial divisions, followed by 2 meiotic 
divisions. Therefore, spermatogonial cells occur in clusters of 2, 4, 8, 16 and 32, 
primary spermatocytes in clusters of 64, secondary spermatocytes in clusters of 128 
and spermatids and sperm in clusters of 256. 

Of special cytological interest in the gametogenesis of both S. montanensis and S. 
caperata, and not reported previously for other lymnaeid snails, are 5 to 7 large chroma- 
tin bodies in each nucleus during early prophase of the first meiotic division of spermato- 
genesis. These chromatin bodies are perhaps another character demonstrating a close 
relationship between the two species. 

S. montanensis has a wide distribution in the western United States in the eastern 
Columbia River and northern Great Basin drainages, from western Montana and Utah 
to southern Idaho and central Nevada. It has the unusual habitat for Lymnaeidae of 
springs or clear mountain streams. S. caperata is found over most of northern North 
America and includes the area of S. montanensis within its distribution. It is found in 
such situations as irrigation ditches and muddy, seasonal waters where S. montanensis 
does not occur. Descriptions of specific habitats and maps of geographic distribution 
(living and fossil) of the two species provide data concerning non -morphological differ- 
ences between the species. The observed geographic separation is due, in part, to 
differences in écologie requirements, but is probably, in part, due to the geologic history 
of the region. S. pilsbryi is known only from the original material from one locality in 
western Utah, and no écologie data are available. 



The common North American snail 
Stagnicola caperata (Say) has hitherto been 
the only species included in the subgenus 
Hinkleyia Baker, 1928. In this paper we 
add S. montanensis (Baker) andS'. pilsbryi 
(Hemphill) to the group. Both of these 
species have been little known up to now, 
but extensive collections show thatS. mon- 
tanensis is widespread in much of the 
western United States. In features of shell 
and anatomy it shows close ties with S. 



caperata. S. pilsbryi (Hemphill) is added 
to this group on shell characters only. 
Anatomical descriptions are by H. J. 
Walter and chromosomal studies by J. B. 
Burch. Taylor and Walter jointly are 
responsible for the discussion of classi- 
fication and for the revised description of 
Stagnicola iflinkleyia) m,ontanensis{Ъ2^aev), 
Taylor is responsible for the discussion 
of variation, distribution and habitat, and 
for notes on S. pilsbryi. 



SUBGENUS HINKLEYIA (LYMNAEIDAE: STAGNICOLA) 



239 



CLASSIFICATION 

The general systematic position of the 
Lymnaeidae as one of the higher Basom- 
matophoran families has long been agreed 
upon. The North American species of the 
family have been most thoroughly studied 
by F. C. Baker, whose two large works of 
1911 and 1928 established the modern 
groupings of Lymnaeidae. Some authors 
(such as Hubendick, 1951) include virtually 
all living species in the single genus 
Lymnaea. Others, as Baker (1911, 1928) 
and Zilch (1959-60) recognize several 
genera. The fact that varying degrees of 
relationship within this group can be 
recognized, primarily on the basis of 
genitalia and radula but to a certain extent 
from shell sculpture, size of nuclear 
whorls, and other features, is a weighty 
objection to including all species in the 
one genus Lymnaea, We believe that such 
a classification obscures more than it 
reveals. 

The genus Stagnicola includes numerous 
species of medium-sized to large Lymnae- 
idae, all found north of the Equator and 
mostly in the north-temperate latitudes. 
Most of the species, and two of the three 
subgenera, are restricted to North Ameri- 
ca. Baker (1928) divided Stagnicola into 
the three subgenera Siog^mcoZa s.s.,Hinkl- 
eyia, and Nasonia. Although we are dealing 
primarily with Hinkleyia, some discussion 
of the relationship of the other two sub- 
genera is necessary for an appreciation of 
the characters of Hinkleyia. 

The only species of the subgenus Nasonia 
that has been examined thoroughly is 
Stagnicola (ЛГ.) bulimoides 1еске11а{НаЫе- 
man). Despite the possession of bicuspid 
lateral teeth and a relatively large nuclear 
whorl it is anatomically not a Stagnicola 
but much closer to Fossaria, another Hol- 
artic lymnaeid genus. This subspecies is 
considered (Walter, 1961) to be a relative 
of Fossaria obrussa (Say), but in the 
present state of knowledge it remains un- 
certain whether all of the group Nasonia 



should be removed from Stagnicola. 

Although Baker (1911, 1928) did not 
discern certain of the distinguishing 
characters of Stagnicola caperata, he 
nevertheless recognized it as an especially 
distinctive species, which he segregated 
by itself in the subgenus Hinkleyia. The 
anatomical characteristics of this species 
have been described in detail (Walter, 
1961) and are summarized elsewhere in 
this paper. From studyof several Ameri- 
can species of Stagnicola s.s. and of S. 
ißinkleyia) caperata and S. (H.) montan- 
ensis it is clear thatЯгn^гZe>'гa has several 
distinctive features, but is so closely simi- 
lar to Stagnicola s.s. that a subgeneric 
rank is appropriate. 

SYSTEMATIC DESCRIPTIONS AND 
FOSSIL AND RECENT DISTRIBUTION 

Family Lymnaeidae 
Genus Stagnicola Jeffreys, 1830 
Subgenus Hinkleyia Baker, 1928 

Genitalia: Penis sheath and penis very 
short and thick, terminal portion of penis 
short and conical; vasdeferens very thick; 
lower prostate flattened, weakly folded, 
roughly D-shaped; vaginal sphincter well 
developed, somewhat eccentric, but not 
ball-like. 

Shell: Nuclear whorl relatively large, 
as in Stagnicola s.s. and Nasonia. Shell 
of small or medium size compared to other 
members of the family; spire longer than 
aperture; columellar fold weak or absent. 
Both axial and spiral sculpture well de- 
veloped. 

Type (by original designation): Stagni- 
cola caperata (Say). 

Distribution: Most of North America, 
as far south as the central United States. 
Middle Pliocene to Recent. 

S. caperata (Say) and S. montanensis 
(Baker) are the only well-known species of 
the group. S. pilsbryi (Hemphill) is in- 
cluded on the basis of shell characters 
alone. 



240 



TAYLOR, WALTER AND BURCH 



Stagnicola (fíinkleyia) montanensis 
(Baker) 

PL I, Figs. 1-17 



Galba montanensis Baker, 1913, Nauti- 
lus 26: 115. 

Lymnaea montanensis Baker: Walker, 
1918, Mich. Univ. Mus. Zool. Mise. Publ. 
6: 94. 

Lymnaea äff. caperata Say: Taylor, 
1956, Wyoming Geol. Assoc. Eleventh 
Ann. Field Conference, Jackson Hole, 
1956, Guidebook: 123, Fig. 3. Love, 1956, 
Wyoming Geol. Assoc. Eleventh Ann. Field 
Conference, Jackson Hole, 1956, Guide- 
book: 92. Love, 1956, Am. Assoc. Petrole- 
um Geologists Bull., 40: 1910. 

Shell of Stagnicola montanensis 

Diagnosis - A species oí Hink le yia with 
evenly convex whorls, regularly tapering 
spire, and glossy shell surface. Spiral 
sculpture, when present, consists of ir- 
regular series of short spirally arranged 
arcs. Axial sculpture of fine to very fine 
growth lines. 

Types - UMMZ 76196, a series of 35 
shells. Baker (1913) specified "Types in 
collection of L. E. Daniels," We restrict 
the type lot to this series which passed 
from Daniels through Bryant Walker and 
retains the original label in Daniel's hand- 
writing. The type locality is "Hayes Creek, 
near Ward, Montana, in the Bitter Root 
Mountains, altitude 3825 feet," L. E. 
Daniels station 13, collected April 25, 
1912. The town of Ward has not been 
traced, but the U. S. Geological Survey 
Hamilton quadrangle (1910) 1:125000 
shows a Hays Creek about 3 miles south 
of Ward Mountain. The creek flows east- 
ward from the Bitter Root Mountains, 
entering the Bitter Root River in the NW 
corner of sec. 1 1, T. 4 N., R. 21 W. Daniels 
probably collected in about the S 1/2 sec. 
3, T. 4 N., R. 21 W., judged by the ele- 
vation he gave. The locality is in the 
Ravalli County, Montana. 

Description - The shell is narrowly 
conical, about 6-13 mm long in adults. 
The outline of the spire varies from flat 



and regularly conical to convex and bullet- 
shaped. The surface of the shell is con- 
spicuously shiny except when covered by 
dirt or algae. Over-all color is brownish 
horn, without the dense red, purple, or 
white markings seen in other Lymnaeidae. 

The nuclear whorl is as in Stagnicola 
s.S. or Nasonia, larger than that of 
Fossaria. The apex of the shell is there- 
fore relatively blunt compared to a 
Fossaria of the same size. The nuclear 
whorl may have the same intensity of 
color as the rest of the shell, or may have 
a deeper, reddish-brown color. 

Larger shells have 5-6 whorls, evenly 
convex or slightly flattened on the sides 
and with a slight shoulder just below the 
suture. The suture is slightly impressed, 
and below the periphery of the preceding 
whorl. It is bordered by a white or light- 
colored band created by thicker shell de- 
posited at the junction of the whorls. Often 
a narrow line of darker (reddish-brown) 
color borders the white band on its lower 
edge. 

The body whorl is about 2/3 of total 
shell length. The aperture is relatively 
small (see measurements. Tables 1-5) 
and regularly elongate -oval, except for 
flattening on the columellar wall and an 
arcuate excision by the parietal wall. The 
outer lip is thin and simple, in profile 
slightly oblique. The columellar border 
of the aperture is straight or weakly 
curved. A columellar fold is often absent, 
and when present is low and poorly defined. 
The parietal lip is thin, appressed to the 
preceding whorl, and passes smoothly into 
the columellar lip with no evident line of 
demarcation at the mid-length of the aper- 
ture. The columellar lip is broadly re- 
flected and leaves an inconspicuous but 
definite umbilical perforation. 

Axial sculpture consists only of weak, 
growth lines, slightly oblique to the axis. 
They may be slightly protractive at the 
suture. Spiral sculpture varies from weak 
and nearly absent to moderately conspicu- 
ous at lOx magnification. It consists of 
spirally arranged seriesof tiny crescentic 
ridges and depressions whose ends point 



SUBGENUS HINKLEYIA (LYMNAEIDAE: STAGNICOLA) 



241 



proximally. These series of crescents are 
variably distinct, but generally weak, and 
vary considerably in strength on a given 
shell and between different shells. They 
tend to be irreguarly wavy and vary also in 
width. Shell and periostracum between 
these spiral series of crescents do not have 
incised lines or raised periostracal ridges 
as in Stagnicola caperata. 

Varices and color bands are not present 
in every lot. When they do occur they 
are usually on all the larger specimens 
in a lot, but are weak and inconspicuous 
compared to these features as usually 
developed in S. caperata. A shell 10 mm 
long may have 3 or 4 varices. These are 
diffuse, with ill-defined edges, and opaque 
in the center. Usually these varices are 
located just proximal to an interruption 
of the shell growth marked by a slight 
descent of the suture and minor change in 
the angle of inclination of the growth lines. 
Color bands almost always are associated 
with varices. They are dark reddish- 
brown with diffuse edges, inconspicuous, 
and next to a varix are immediately distal. 
Shells found empty usually have a wash of 
deeper color just inside the aperture even 
when no varix is present. 

Measurements, variation in proportions 
- The most conspicuous variation in Stag- 
nicola montanensis is in size and pro- 
portions. Ideally one would analyze this 
variation by biométrie analysis of selected 
samples. Unfortunately the number of 
specimens available is inadequate for a 
consistent treatment, in this way, of 
samples representing all the observed 
variation. In order to document the range 
of size and proportions in the species parts 
of the larger representative samples (3 
recent and 1 fossil) have been measured 
as discussed below and shown in Tables 
1-5. 

Cottonwood Creek, Franklin County, 
Idaho (Table 1): This sample includes one 
of the two largest specimens (14.6 mm 
long) seen. It is from the locality de- 
scribed on p 270. The shells here are 
fairly narrow, turriform in many cases. 
On shape alone, many specimens could be 
distinguished from the more broadly 



conical S. caperata. 

Driggs, Teton County, Idaho (Table 2): 
A series from the locality described on p 
270 is of larger average size than most 
series of shells from elsewhere. It in- 
cludes one of the two largest specimens 
(14.6 mm long) seen. The shells are glo- 
bose, often indistinguishable from Stag- 
nicola caperata in form, and almost com- 
pletely lack spiral sculpture. This lot 
of smooth, globose shells is more like the 
series from north of Driggs and from the 
type locality than like shells from other 
localities. 

Cottonwood Creek, Twin Falls County, 
Idaho (Table 3): All the shells from south- 
central Idaho are closely similar to one 
another. They have evenly convex whorls 
which are more elongate than in many other 
lots, or which may show a slight shoulder 
toward the suture. Theoutlineof the spire 
is usually slightly convex. Often the tip of 
the spire is etched or eroded away. In 
this series from Cottonwood Creek 13 
specimens were measured which had un- 
eroded apices and a length of more than 
8 mm. Eleven other specimens over 8 
mm long were not measured because of 
eroded spires. 

Pleistocene, locality 22328 (for data on 
this and other localities see Appendix p 
270), Bannock Co., Idaho (Table 4): Shells 
from localities 22328 and 22410 in Marsh 
Creek valley, Bannock County, Idaho, are 
the smallest S. montanensis seen. Except 
for size they are like other samples, for 
the surface sculpture and proportions (see 
Table 5) are not unusual. 

The measurements of Stagnicola 
montanensis which have been given in 
Tables 1-4 are an adequate indication of 
the variation in the larger shells of these 
samples, which encompass the range of 
variation of the species. The measure- 
ments cannot all be compared on the same 
basis, however, because of the small 
numbers of specimens in certain size- 
classes. The more nearly comparable 
measurements have been summarized in 
Table 5. 

Comparisons of shells - The relatively 
large nuclear whorl and shiny surface 



242 



TAYLOR, WALTER AND BURCH 
PLATE I 




SUBGENUS HINKLEYIA (LYMNAEIDAE: STAGNICOLA) 



243 





Д Cottonwood Cr., Franklin Co. 

A Driggs, Teton Co. 

О Cottonwood Cr,, Twin Falls 

% Loc. 22328, Валпоск Co. 



Width oí SheU (mm) 



FIG. 1. Shell of Stagnicola montanensis, 
x7.5, from type locality, Hays Creek, 
Ravalli County, Montana. USNM 570589. 
Length 9.7 mm, width 5.7 mm; 5+ whorls. 



FIG. 2. Shell measurements of four 
samples of S. montanensis . Diagonal lines 
represent linear regression of shell width 
on shell length. The regression line 
equation for the four samples are as fol- 
lows: Cottonwood Creek, Twin Falls Co., 
Idaho, W= .12 + .48 L; Driggs, Teton Co., 
Idaho, W= 1.5 + .37 L; Cottonwood Cr., 
Franklin Co., Idaho, W= 1.51 + .30 L; 
Pleistocene, Bannock Co., Idaho, W= 1.08 + 
.34 L. 



PLATE I 

FIGS. 1, 2. Twin Falls Co., Idaho. Head of tributary of South Fork Shoshone Creek, 
SW 1/4 SW 1/4 sec. 27, T. 14 S., R. 18 E. Length 7.6 mm, 4 3/4 whorls. USNM 633882. 

FIG. 3. Same locality. Length 7.6 mm, spire eroded. USNM 633883a. 

FIGS. 4, 5. Same locality. Length 7.4 mm, spire eroded. USNM 633883b. 

FIGS. 6, 7. Twin Falls Co., Idaho. Cottonwood Creek near center of south edge of sec. 
3, T. 15 S., R. 18 E. Length 7.8 mm, 4 3/4 whorls. USNM 633885a. 

FIGS. 8, 9. Same locality. Length 9.3 mm, 5 whorls. USNM 633885b. 

FIGS. 10, 11. Lincoln Co., Wyo. Pasture at Bedford. Length 10.4 mm, 5 1/2 whorls. 
USNM 536403a. 

FIGS. 12, 13. Lincoln Co., Wyo. Grassland at Grover. Length 8.7 mm, 6 whorls. 
USNM 536407c. 

FIGS. 14, 15. Same locality. Length 10.8 mm, 6 1/4 whorls. USNM 536407a. 

FIGS. 16, 17. Same locality. Length 10.3 mm, 6 1/2 whorls. USNM 536407b. 



244 TAYLOR, WALTER AND BURCH 

TABLE 1. Measurements (in mm) of shells^ of Stagnicola montanensis from Cotton- 
wood Creek, Franklin County, Idaho 



Shell 


Aperture 1 


Number 






Ratio of 






Ratio of 


of 


Length 


Width 


Le/Wi 


Length 


Width 


Le/Wi 


Whorls 


13.2 


5.4 


2.45 


4.9 


3.1 


1.54 


6 1/2 


10.9 


4.9 


2.24 


4.0 


2.6 


1.55 


6 1/4 


9.7 


4.3 


2.26 


3.6 


2.3 


1.56 


6 1/4 


14.6 


5.9 


2.49 


6.0 


3.3 


1.83 


6 


10.3 


4.3 


2.40 


4.3 


2.9 


1.50 


6 


13.9 


5.7 


2.42 


5.4 


3.0 


1.81 


5 3/4 


10.7 


5.1 


2.08 


4.6 


3.1 


1.45 


5 3/4 


9.4 


4.6 


2.06 


4.0 


2.6 


1.55 


5 3/4 


9.0 


4.3 


2.10 


3.4 


2.3 


1.50 


5 3/4 


8.9 


4.4 


2.00 


3.6 


2.4 


1.47 


5 3/4 


8.7 


4.3 


2.03 


3.7 


2.3 


1.62 


5 3/4 


8.7 


4.1 


2.10 


3.8 


2.1 


1.80 


5 3/4 


8.7 


3.9 


2.26 


3.4 


2.1 


1.60 


5 3/4 


8.3 


3.7 


2.23 


3.1 


2.1 


1.47 


5 3/4 


8.3 


3.9 


2.14 


3.3 


2.0 


1.64 


5 3/4 


8.1 


3.7 


2.19 


3.4 


2.1 


1.60 


5 3/4 


8.4 


4.3 


1.97 


3.6 


2.3 


1.56 


5 1/2 


8.4 


4.0 


2.10 


3.6 


2.1 


1.67 


5 1/2 


8.4 


3.9 


2.18 


3.4 


2.0 


1.71 


5 1/2 


8.3 


3.7 


2.23 


3.4 


2.1 


1.60 


5 1/2 


8.3 


3.7 


2.23 


3.3 


2.1 


1.53 


5 1/4 



'^Twenty-one shells, all those over 8 mm long, were measured 



distinguish shells of Stagnicola montan- 
ensis from those of Fossaria, which they 
may resemble in size and shape. The 
elongate shape and the spiral sculpture 
distinguish this species from Nasonia, 
which it resembles in size of nuclear 
whorl, weak or absent columellar fold, and 
smooth shell surface. The weak or absent 
columellar fold and relatively smaller 
aperture distinguish S. montanensis from 
extreme variations of S. elodes or its 
close relatives. 

Stagnicola caperata is the species most 
similar to S. montanensis, and the shells 
of these two are the most difficult to 
separate. Many specimens of S. montan- 
ensis are narrowly elongate (PI. I, Fig. 
14-15) and thus differ from the usually 
more swollen shells of S. caperata (PL II, 
Fig. 10-12). But the two species overlap 
considerably in variation of shape and this 
character is not dependable. Surface 



texture and sculpture are the only con- 
sistently reliable criteria for distinction 
of the species. 

Most specimens in most samples of 
Stagnicola caperata bear raised spiral 
ridges of periostracum which run in in- 
cised lines. Characteristically these 
spiral features of sculpture are relatively 
conspicuous (PI. II, Fig. 2-3, 8-12). Both 
periostracal ridges and incised lines are 
diagnostic of S. caperata. A shiny surface, 
without such sculpture, is characteristic 
of S. montanensis. The shells of S. 
montanensis with well-developed sculp- 
ture (PI. I, Fig. 1, 5, 7) show spirally 
arranged series of tiny crescents whose 
ends point away from the outer lip. They 
have no periostracal ridges or incised 
lines. 

The shells most difficult to identify are 
those in which the sculpture is weak. 
Elongate, narrow shells of S. caperata 



SUBGENUS HINKLEYIA (LYMNAEIDAE: STAGNICOLA) 



245 



TABLE 2. Measurements (in mm) of shells^ of Stagnicola montanensis from Driggs 
Teton County, Idaho 



Shell 


Aperture 


Number 


Length 


Width 


Ratio of 

Le/Wi 


Length 


Width 


Ratio of 

Le/Wi 


of 
Whorls 


14.6 


6.7 


2.17 


6.3 


4.0 


1.57 


6 1/4 


14.4 


6.7 


2.15 


5.9 


3.6 


1.64 


6 1/4 


12.3 


6.0 


2.05 


5.1 


3.4 


1.50 


6 1/4 


13.0 


6.6 


1.98 


6.1 


3.4 


1.79 


6 


13.1 


6.3 


2.09 


5.6 


3.4 


1.62 


6 


13.0 


6.0 


2.16 


5.3 


3.3 


1.61 


6 


12.1 


6.4 


1.89 


5.3 


3.1 


1.68 


6 


11.7 


5.7 


2.05 


4.9 


3.0 


1.62 


6 


11.6 


5.7 


2.02 


4.9 


3.0 


1.62 


6 


14.3 


7.6 


1.89 


6.4 


3.9 


1.66 


5 3/4 


12.1 


6.6 


1.85 


5.6 


3.3 


1.70 


5 3/4 


12.1 


5.9 


2.07 


5.4 


3.3 


1.65 


5 3/4 


11.9 


6.1 


1.93 


5.1 


3.1 


1.64 


5 3/4 


11.3 


5.6 


2.02 


4.9 


2.9 


1.70 


5 3/4 


11.0 


5.7 


1.93 


5.3 


3.3 


1.61 


5 3/4 


10.9 


5.6 


1.95 


5.0 


2.9 


1.75 


5 3/4 


10.7 


5.1 


2.08 


4.7 


2.9 


1.65 


5 3/4 


10.4 


5.6 


1.87 


5.0 


3.0 


1.67 


5 3/4 


10.4 


5.1 


2.02 


4.4 


2.9 


1.55 


5 3/4 


10.3 


5.4 


1.90 


4.6 


2.9 


1.60 


5 3/4 


10.1 


5.0 


2.03 


4.6 


2.9 


1.60 


5 3/4 


10.0 


5.1 


1.94 


4.9 


3.0 


1.62 


5 3/4 



^Twenty-two shells, all those with at least 5 3/4 whorls, were measured. 



TABLE 3. Measurements (in mm) of shells" of Stagnicola montanensis from Cotton- 
wood Creek, Twin Falls, Idaho 



Shell 


Aperture 


Number 






Ratio of 






Ratio of 


of 


Length 


Width 


Le/Wi 


Length 


Width 


Le/Wi 


Whorls 


9.3 


4.1 


2.24 


3.9 


2.3 


1.69 


5 1/4 


9.7 


4.7 


2.06 


3.9 


2.6 


1.50 


5 


9.3 


4.3 


2.16 


3.9 


2.4 


1.59 


5 


9.1 


4.4 


2.06 


4.0 


2.6 


1.55 


5 


9.0 


4.6 


1.97 


4.1 


2.4 


1.70 


5 


8.9 


4.6 


1.94 


4.0 


2.4 


1.65 


5 


8.9 


4.7 


1.88 


4.1 


2.6 


1.61 


5 


8.7 


4.3 


2.03 


4.0 


2.4 


1.65 


5 


8.6 


4.3 


2.00 


3.9 


2.4 


1.59 


5 


8.4 


4.3 


1.97 


3.9 


2.1 


1.80 


5 


8.1 


4.0 


2.04 


3.6 


2.1 


1.67 


5 


8.3 


4.1 


2.00 


3.9 


2.4 


1.59 


4 3/4 


8.1 


4.0 


2.04 


3.9 


2.4 


1.59 


4 3/4 



"Thirteen specimens of more than 8 mm with uneroded apices. 



246 



TAYLOR, WALTER AND BURCH 



TABLE 4. Measurements (in mm) of Pleistocene shells'' of Stagnicola montanensis 
from locality 22328, Bannock County, Idaho 



Shell 


Aperture 




Number 






Ratio of 






Ratio of 


of 


Length 


Width 


Le/Wi 


Length 


Width 


Le/Wi 


Whorls 


7.9 


3.3 


2.39 


3.0 


1.7 


1.75 


6 


6.9 


3.3 


2.08 


2.7 


1.7 


1.58 


6 


6.9 


3.1 


2.18 


2.6 


1.6 


1.64 


5 3/4 


6.1 


2.9 


2.15 


2.1 


1.4 


1.50 


5 3/4 


6.7 


2.9 


2.35 


2.6 


1.4 


1.80 


5 1/2 


6.7 


3.1 


2.14 


2.6 


1.7 


1.50 


5 1/2 


6.4 


3.0 


2.14 


2.3 


1.6 


1.45 


5 1/2 


6.4 


3.1 


2.04 


2.7 


1.6 


1.73 


5 1/4 


6.1 


3.0 


2.04 


2.6 


1.6 


1.63 


5 1/4 


6.0 


3.0 


2.00 


2.4 


1.4 


1.70 


5 1/4 


5.9 


2.9 


2.05 


2.6 


1.6 


1.64 


5 1/4 


5.9 


3.0 


1.95 


2.3 


1.6 


1.45 


5 1/4 


5.5 


2.6 


2.16 


2.1 


1.4 


1.50 


5 1/4 


5.9 


2.9 


2.05 


2.4 


1.4 


1.70 


5 


5.9 


3.0 


1.95 


2.6 


1.6 


1.64 


5 


5.7 


2.7 


2.10 


2.1 


1.4 


1.50 


5 


5.7 


2.7 


2.10 


2.1 


1.6 


1.36 


5 


5.5 


2.7 


2.05 


2.3 


1.4 


1.60 


5 


5.3 


2.9 


1.85 


2.3 


1.4 


1.60 


5 


5.3 


2.6 


2.05 


2.1 


1.3 


1.67 


5 


5.3 


2.7 


1.95 


2.1 


1.3 


1.67 


5 


5.3 


2.7 


1.95 


2.0 


1.4 


1.40 


5 


5.3 


2.4 


2.18 


2.0 


1.3 


1.56 


5 


5.3 


2.6 


2.06 


2.3 


1.3 


1.78 


5 


4.9 


2.6 


1.89 


2.0 


1.3 


1.56 


5 


4.7 


2.3 


2.06 


1.9 


1.1 


1.63 


5 



7Twenty-six specimens, all those with at least five whorls, were measured. 



without periostracal ridges and with no 
well incised lines (PI. II, Fig. 4-7) are 
the closest approach to S. montanensis. 
The two figured specimens are surely 
identifiable as S. caperata, only because 
faint traces of spiral lines cutting the 
growth lines are discernible at 30x-40x 
magnification with strong oblique light. 
These two are from a lot which includes 
also more typical shells of S. caperata 
(PI. II, Fig. 2, 3) with stronger sculpture 
and stouter form. 

The shells of S. montanensis most 
similar to those of S. caperata have 
sculpture, but weak sculpture only. The 
tiny crescents may then become shorter 
and shorter until they are only series of 



short bars arranged in spiral lines. When 
the surface of such shells is examined by 
strong oblique light, one can observe that 
the spiral lines are not incised and may be 
traceable to the more usual series of 
crescents. 

Original description - "Shell of medium 
size, rather thin, translucent, ovate- 
turreted; periostracum light horn color; 
surface shining, lines of growth distinct, 
crossed by very fine wavy spiral lines; 
whorls six, convex, the body whorl some- 
what obese; sutures deeply impressed; 
spire acute, longer than the aperture; 
aperture ovate, outer lip thin; inner lip 
wide, somewhat triangular, reflexed over 
the umbilical region; there is no distinct 



SUBGENUS HINKLEYIA (LYMNAEIDAE: STAGNICOLA) 



247 



TABLE 5. Summary of measurements (in mm) of Stagnicola montanensis shells^ from 
four localities in Idaho 





Cottonwood 




Cottonwood 






Creek, 


Driggs, 


Creek, 


Pleistocene 




Franklin Co. 


Teton Co. 


Twin Falls Co. 


Bannock Co. 


Shell length 


9.34 


11.19 


8.87 


5.39 




(8.1-13.9) 


(10.0-14.3) 


(8.1-9.7) 


(4.7-5.9) 


Shell width 


4.34 


5.72 


4.42 


2.68 




(3.7-5.7) 


(5.0-7.6) 


(4.0-4.7) 


(2.3-3.0) 


Aperture length 


3.79 


5.07 


3.94 


2.17 




(3.1-5.4) 


(4.4-6.4) 


(3.6-4.1) 


(1.9-2.6) 


Aperture width 


2.37 


3.10 


2.40 


1.37 




(2.0-3.1) 


(2.9-3.0) 


(2.1-2.6) 


(1.1-1.6) 


Ratio of shell 


2.15 


1.96 


2.01 


2.02 


length/width 


(2.00-2.42) 


(1.85-2.08) 


(1.88-2.16) 


(1.85-2.18) 


Ratio of aperture 


1.59 


1.65 


1.63 


1.59 


length/width 


(1.45-1.81) 


(1.55-1.75) 


(1.50-1.80) 


(1.36-1.78) 


No. of whorls 


5 3/4 


5 3/4 


5 


5 


No. of specimens 


11 


13 


10 


13 



ÔThe mean is foliOwed by the range in parentheses. All measurements are of specimens 
in the same size-class (based on number of whorls). 



axial plait, but the inner lip is slightly 
indented where it touches the parietal wall; 
the umbilical chink is narrowly open. 
There are two rest period marks on one 
adult specimen. 

Length 14.00; width 6.50; aperture 
length, 6.80; width 4.00 mill, adult. 

Length 9.00; width 5.00; aperture length, 
5.50; width 3.00 mill. juv. 

Length 14.25; width 8.00; aperture 
length, 7.00; width 4.00 mill, adult. 

Length 10.00; width 5.25; aperture 
length, 5.00; width 3.00 mill, juv." 
(Baker, 1913, p 115-116). 

Anatomy and radula of Stagnicola montan- 
ensis compared to other Lymnaeidae 

A single series of S. montanensis was 
made available for anatomical study. The 
specimens were collected by the senior 
author from a tributary of the South Fork 
of Shoshone Creek, Twin Falls County, 
Idaho. They had been well relaxed with 
menthol, killed and fixed with formalin. 



and then had been preserved in 70% alco- 
hol. Their shells were from about 4 mm 
to about 9 mm long. Sixteen of the snails, 
including the largest and smallest, were 
dissected, and all of the organ-systems 
were examined in some detail. One radula 
was studied also. 

In this paper, characters of taxonomic 
concern will be described, and particularly 
prominent features of S. montanensis, 
such as the pattern of palliai pigmention. 
Certain descriptive material is included 
to illustrate some basic aspects of 
lymnaeid anatomical organization which 
have not been recorded or clarified ade- 
quately in any previous publication. The 
reproductive system and the radula are of 
particular taxonomic interest and are de- 
scribed in detail; some information is 
given on sexual maturity as related to 
shell-size. 

A critical evaluation of the taxonomic 
significance of the anatomical characters 
of S. montanensis is given below. This 
evaluation depends very heavily on com- 



248 



TAYLOR, WALTER AND BURCH 



parative data which were obtained in an 
earlier study of many species of Lymnae- 
idae; most of these data have been 
recorded, only in an unpublished disser- 
tation (Walter, 1961), although a brief 
report on the results of that study appeared 
elsewhere (Walter, 1959). Here, only a 
limited amount of the more essential data 
can be given. The anatomical terminology 
used in this paper is tentative and was 
partly devised by the author; it corre- 
sponds to that employed in the dissertation 
mentioned, where the terms are elucidated 
by many detailed illustrations in an account 
of the morphology of S. (Stagnicola) emar- 
ginata serrata (ДаШетап). Much that 
was observed about the morphology of S. 
montanensis, but is not included in this 
paper, as well as some of what is described 
here is essentially no different from what 
is given about S. e. serrato in that account. 
Special problems inherent in this kind 
of study affect the interpretation of obser- 
vations made, and as such, they deserve 
explanation. The narcotization-killing 
process when most successfully applied to 
a collection of snails en masse, commonly 
results in considerable contraction of the 
tentacles of all of the specimens, while 
causing the sole of the foot of most indi- 
viduals to expand, and especially to 
broaden, beyond the dimensions that it 
normally would show in life when function- 
ing in locomotion. Concomitantly, indi- 
vidualistic reaction of specimens to the 
narcotization-killing process results in 
various modifications of the form of the 
body and of internal organs. The organs 
as a whole are plastic and are easily 
distorted by tensions and pressures. 
Muscular or glandular activity may cause 
the organs to be altered grossly in their 
shape and dimensions during their normal 
functions. Therefore, the "normal" or 
"intrinsic" form of an organ cannot be 
readily defined, and must be considered in 
relation to particular postures of that 
organ. Such an organ may assume a wide 
variety of normal postures and may react 
to a "relaxing" chemical in a variable way. 
Even in a well-relaxed snail the muscular 
organs often seem to have reacted in an 



uncoordinated way, causing some struc- 
tures to be "relaxed" and causing others 
to be contracted. For example, in a series 
of specimens, according to the individual, 
a greatly retracted penis may occur in a 
greatly extended penis sheath, the penis 
may be retracted while the sheath is ex- 
tended, both penis and sheath may be 
retracted, or both may be extended. 
The vagina, to give another example of 
such "artifact-variation", may be found 
to be greatly contracted and narrow, or 
else greatly inflated, in individuals of one 
series; when contracted, the organ may be 
very firm and quite strongly muscular, 
and when inñated, its walls may be ex- 
tremely thin and delicate and may seem to 
be only very weakly muscular. Such vari- 
ation, superimposed on the genetically 
determined, intrapopulation and inter- 
population anatomical variation, that 
seems to be of considerable magnitude 
in lymnaeids generally, makes it difficult 
to judge objectively whether a particular 
organ of a particular individual or in a 
particular population may "really" differ 
morphologically from that of another indi- 
vidual or from that in another population. 

In taxonomic work on such snails at the 
species-level, one must then seek for 
minor consistencies among gross incon- 
sistencies, and accordingly, statements 
about real differences pertaining to such 
structures are likely to be inextricably 
involved with subjective impressions and 
can be subject to extensive qualification. 

Miscellaneous characters and pigmen- 
tation of S. montanensis - The head-foot 
mass and the tentacles of S. montanensis 
are apparently particularly slender in life. 
In the best-relaxed specimens the 
tentacles are mostly rather slender and 
pointed, despite being contracted, while 
the sole of the foot is about twice as long 
as it is wide, which is fairly narrow for 
that of a lymnaeid. 

In S. montanensis there is a groove 
which runs along the peripheral border of 
the mantle collar and this groove divides 
that border into two shelf-like structures, 
the one above the other. A homologous 
development occurs in at least some other 



SUBGENUS HINKLEYIA (LYMNAEIDAE: STAGNICOLA) 



249 



Lymnaeidae. In S. montanensis these 
"shelves" are readily noticeable on the 
whole, and in certain individuals the lower 
one projects distinctly and even conspicu- 
ously beyond the other. The "shelves" in 
other Lymnaeidae are usually not nearly 
so well developed. 

The renal organ of several specimens of 
S. montanensis was examined and it was 
observed to be quite slender for a 
lymnaeid. Running along the underside of 
that organ there were two well-developed 
and close-set parallel muscular bands, 
which constitute "the renal muscle" 
(Hubendick, 1951). The 3 jaws were bright 
brownish-orange. The dorsal jaw was 
noted to be unusually narrow and rather 
asymmetrical; its free margin, which ex- 
hibited no cusps, was broadly excavated 
in the center, while its dorsal margin of 
attachment was broadly arched. 

The S. montanensis studied were more 
darkly colored overall than are most 
lymnaeids, and they showed an unusually 
prominent pattern of pigmentation in the 
palliai areas. The pigment mostly occur- 
red as minute dusky flecks which were, in 
part, diffusely distributed and which were 
partly concentrated in particular parts of 
the body. The larger specimens tended to 
be darkest. The head-foot region was dark 
gray to medium gray due to a general sub- 
surface suffusion with the dusky flecks. 

Immediately over the pneumostome, on 
the far right side of the mantle collar, there 
is a large, diffuse, sub-surface smudge of 
light gray to blackish color; this smudge 
occupies the area of the "hypobranchial 
gland". Above this "gland", over the right 
side of the lung and against the inside shell- 
surf ace, there runs an intensely black band 
parallel to the free edge of the mantle 
collar. The remainder of the surfaces 
which lie against the inside of the shell in 
the region of the lung and kidney are coated 
with a mottled film of black pigment. This 
film is interrupted by light oval areas with 
diffuse edges. These ovals are much 
larger, relatively, in the smaller speci- 
mens, particularly in those about 4 mm 
in shell length, in which the pigmentation 
is largely restricted to narrow zones that 



form a reticulate pattern. In the larger 
individuals the ovals tend to be obliterated 
by broadening of the dark zones. From 
the lung region the heavy pigmentation 
continues posteriorly onto the coiled, sac- 
like part of the mantle (tunica propria) 
that encloses the earlier whorls, but it is 
confined to the posterior (spireward) half 
of the outer face of each coil. These dark 
areas are irregularly but sharply de- 
limited from the more anterior parts of 
the whorls, which are very pale. Within 
the dark areas, the pigment forms a 
mottled dusky-gray to blackish pattern 
which in young specimens is clearly seen 
to be made up of numerous tiny dark spots 
and dashes, while a greater concentration 
of pigment in these areas forms a narrow 
black zone, interrupted by light oval spots, 
that runs along the posterior edge of each 
whorl. The mantle collar anterior to the 
lung is gray owing to a subsurface suf- 
fusion with dusky pigment, and on it there 
are some irregular black to dusky-gray 
small blotches with diffuse edges. Much 
of the internal structure of the animal 
exhibits a pronounced, minutely granular 
pigmentation, even in immature speci- 
mens. The arteries and the digestive 
system are quite dark. Longitudinal dusky 
bands are conspicuous along the length of 
the esophagus and the two diverticula of 
the osphradium are flecked with black. 
Hermaphroditic reproductive organs - 
The ovotestis of S. montanensis is largely 
invested by, and tightly bound to, a complex 
of tissues consisting of the liver, con- 
nective fibers, and elements of the vascu- 
lar system. The exact shape of the gonad 
was not determined, but it was seen to 
consist of a number of large lobes, made 
up of compactly arranged follicles. The 
follicles do not project from the surface 
of the lobes and are so intimately bound 
together that they could not be separated. 
The surface of the lobes showed yellow 
spots and irregular rusty-orange flecking 
arranged in a vaguely reticulate pattern 
against a general creamy -white back- 
ground. Granules and yellow ova, applied 
to the internal walls of the follicles, 
account for the pattern and sperm account 



250 



TAYLOR, WALTER AND BURCH 



for the background color. The remaining 
part of the hermaphrodite system, the 
hermaphroditic duct, arises near the an- 
terior end of the gonad. The duct is a 
long tube which proceeds cephalad into the 
visceral haemocoel, in which it partly 
lies free. In all specimens it showed two 
grossly different portions. The first 
portion is somewhat the longer, and is 
broad and bulky, although it is very narrow 
at its origin on the anterior part of the 
gonad. It is considerably contorted, es- 
pecially near its origin; its walls are thin 
and it contains a compact mass of sperm, 
which causes its bulkiness and lends it a 
creamy white color. The bulk of the 
sperm mass projects into and fills out 
abundant crowded seminal vesicles, which 
swell out laterally from opposite sides 
of the broad central duct to form two 
uniseriate rows. The arrangement of the 
vesicles indicates a bilateral symmetry 
although the vesicles are rather irregular 
in size and arrangement near the beginning 
of the duct. The second, distal segment of 
the hermaphroditic duct is a much narrow- 
er, slender, and mostly smooth cylindrical 
tube, that tapers somewhat toward its 
terminus. 

Female genitalia - The female and male 
genital systems arise at the terminus of 
the hermaphroditic duct, and firstly form 
a compact complex of glandular organs 
massed around that point. The albumen 
gland and uterine complex of the female 
system are the most conspicuous elements 
of this mass. These structures, when 
separated, are seen to be much the same 
as in other lymnaeids. However, they are 
more compactly arranged, and more 
mucoid and more swollen than in some 
species. The uterine complex consists of 
an apical uterine pouch, a uterine coil, and 
a free uterine arm, which makes up suc- 
cessive portions of the tract. The albumen 
gland, which is large and roundly tri- 
angular in outline, lies against this 
complex and empties into the apical pouch 
by a short small duct. A small fertili- 
zation pocket was assumed to be present 
at the base of the albumen gland but it was 
not demonstrated unequivocally. The 



uterine coil is the bulkiest organ in the 
complex and is especially mucoid. The 
free uterine arm is tubular and elongate; 
its juncture with the succeeding portion 
of the tract, the neck of the oothecal gland, 
is hidden by two structures appended to 
the tract at that point. These structures 
are the oothecal gland pouch and the 
muciparous (nidamental) gland. The pouch 
is flattened, slightly broadened, and 
roundly diamond- shaped or sometimes 
short and angularly truncate; it is a blind 
reverse extension of the tubular neck of 
the oothecal gland and it is rather small 
and difficult to demonstrate. The muci- 
parous gland is bulky, bulbous and roundly 
angular in outline: it attaches broadly to 
an opening in the base of the pouch, and 
partly to the end of the free uterine arm 
which attaches at the same opening and 
which is tightly sandwiched between the 
gland and the pouch. Numerous coarse and 
compactly arranged glandular internal 
lamellae make up the bulk of the muci- 
parous gland. 

The main body of the oothecal gland 
(oviducal bulb, birnenförmiger Körper, 
first accessory albuminiparous gland of 
authors) is a swollen portion of the female 
tract in which internal glandular lamellae, 
largely diagonal to the tract, are greatly 
developed. The first part of the gland, or 
its neck, is short and stout in comparison 
with that in some other lymnaeids, being 
about half the length and half the diameter 
of the main body. The latter is broadly 
spindle-shaped or nearly cylindrical and 
is small compared to that of some Lymnae- 
idae. In a specimen 8.9 mm in shell- 
length the organ contained 11 to perhaps 
13 large lamellae, and possibly some 
smaller ones. The ventral raphe of the 
organ appears to be broad, but was not 
clearly discerned. The last large part of 
the female system is the vaginal tract, 
which is succeeded by the short vagina 
proper leading to the female pore on the 
right side of the animal. The diameter of 
the vaginal tract for its whole length is 
about 3/4 that of the oothecal gland pre- 
ceding it. It is rather flattened dorso- 
ventrally. Its distal half is thick-walled, 



SUBGENUS HINKLEYIA (LYMNAEIDAE: STAGNICOLA) 



251 



highly muscular, and hardly glandular, 
as a result of progressive differentiation 
from the preceding gland. The vaginal 
tract rapidly tapers in giving way to the 
vagina proper and there the duct of the 
spermatheca is appended to it. The duct 
of the spermatheca, which is somewhat 
shorter than the combined length of the 
vagina and oothecal gland, passes from its 
origin on the right to the left side of the 
animal and expands terminally to formthe 
spermatheca, which lies against the peri- 
cardium. The spermatheca, at least in 
some specimens, exhibits pronounced, ir- 
regular, yellowish internal ridges and 
seems to be particularly variable in size 
and shape. It was sometimes as large as 
the oothecal gland and sometimes much 
smaller. In one specimen it was very 
small and shaped like a short sausage, 
but in nearly all cases it was observed to 
be more or less angular and usually it was 
found to be roundly quadrangular. The 
duct attaches far off-center on the sper- 
matheca, at an angle to the organ. It is 
rather thick in its upper part and is ex- 
tremely thick and muscular toward its 
junction with the vagina, where it is usually 
nearly as broad as the vagina, although 
it was only about 1/3 as broad in one case. 
Circular or transverse muscle elements 
partly proceeding from the base of the 
spermathecal duct form a strong vaginal 
sphincter against and below the base of 
the duct. The sphincter is not abruptly 
set off from the musculature of the pre- 
ceding parts and its upper border is 
disposed diagonally to the vaginal axis. 
It may bulge out, but not markedly, as a 
distinctly spheroidal structure, as is the 
case in some lymnaeids. Passing through 
the sphincter, the tract becomes a short, 
fine tube attaching at the female pore. The 
pore is a relatively small slit with two 
weakly defined lips, located high on the 
neck of the animal, close to the insertion 
of the mantle collar. 

Male genitalia - An upper prostate, a 
lower prostate, a vas deferens and a 
penial complex, form the successive di- 
visions of the male tract. The upper 
prostate is a long, fleshy-glandular. 



flattened tube of a light color; it abruptly 
and greatly increases in diameter immedi- 
ately beyond itsvery narrow point of origin 
at the terminus of the hermaphroditic duct. 
As it swells it gives rise to a prominent 
lateral evagination, the prostate pouch. 
The pouch contrasts with the prostate in 
being darkly pigmented, and in being very 
thin -walled; it is curved and much flattened 
and wrinkled and about twice as long as 
it is broad, having nearly the width of the 
adjoining prostate. Most of the pouch is 
tightly sandwiched between the uterine 
complex and the albumen gland. The upper 
prostate is rather broad, thick-walled and 
twisted in its upper part; further down it is 
largely flattened against the underside of 
the oothecal gland andbecomes narrow and 
thin toward its terminus. The lower 
prostate is a swollen and highly glandular 
division of the male tract, set off by a 
constriction from the upper prostate, 
which it resembles in color and texture; 
it is large to very large and may be almost 
the size of the whole female complex. This 
organ is somewhat flattened and is some- 
what longer than broad. Its right edge is 
very shallowly concave, while the opposite 
edge is strongly convex, so that it tends to 
be bean-shaped or nearly D-shaped. The 
upper side of the lower prostate that is 
partly appressed to the underside of the 
oothecal gland is quite flat or nearly so. 
The wall of this flat side is invaginated 
longitudinally, so as to form a single 
internal fold traversing its length. For 
the most part, this line of invagination 
is obliterated by apparent fusion of the 
juxtaposed walls. In cross-section the 
fold forms a solid, roundly triangular 
projection; it is rather weak although its 
walls are considerably thickened. As 
compared to that found in some other 
species, the wall of the lower prostate is 
rather thin and the lumen is rather large. 
At the distal, lower end of the organ the 
internal fold shows externally as a shallow 
groove which divides that end into two, 
low, rounded protuberances. Arising near 
the end of the prostate but well on its 
underside, at the end of the groove, is the 
tubular vas deferens. The vas represents 



252 



TAYLOR, WALTER AND BURCH 



an abrupt and great reduction in the dia- 
meter and glandularity of the tract; along 
its length it is highly muscular, chiefly 
due to devlopment of circular muscles. 
It tends to project from the prostate 
parallel to the axis of that organ, but soon 
curves to the right to pass into the body 
wall near the female pore. It then pro- 
ceeds directly into the anterior part of 
the head-foot organ and then passes out of 
the body wall at the base of the right 
tentacle by the male pore. It forms a long 
free loop in the major anterior haemocoel 
of the body and then terminates at the 
penial complex. The vas shows no con- 
striction at its origin where it is about 
1/4 the diameter of the lower prostate. 
Although it tapers somewhat gradually 
toward its terminus it is notably stout 
overall, except where it is most narrowed 
near its attachment to the copulatory 
organ. That part of the vas deferens in 
the body wall shows through the tissues, 
and its stoutness is easily seen on ex- 
ternal examination of the animal. 

The penial complex begins as a tubular, 
abrupt broadening of the male tract, the 
penis sheath. This sheath is succeeded 
distally by a longer and more expanded 
tube, the preputium, which attaches to the 
body wall around the male pore. Enclosed 
in the penis sheath is the penis which 
largely consists of muscular elements de- 
veloped around a direct continuation of 
the vas deferens. The penial complex is 
of moderate to fairly small size. The 
sheath is very short and broad; its width 
is 2/3 of its length, or less. Its length 
was observed to be 1/3 to 1/2 that of the 
preputium. The sheath is somewhat 
tapered distally, and tends to be much- 
swollen proximally where it is 2/3 to 3/4 
the diameter of the preputium. The 
swelling of the end is due to unusual de- 
velopment of internal "proximal cham- 
bers". The chambers are crowded around 
the base of the penis and may extend down 
into the sheath well beyond the penial base; 
they are very irregular in shape and have 
glandular walls. The preputium may be 
moderately to quite stout, and tends to be 
fusiform; in smaller specimens especially 



it may be much swollen proximally and may 
show considerable distad attenuation. The 
swelling of the preputium is caused by a 
large "velum" that fills its inner end. This 
velum is a fleshy ring attached along the 
internal line of junction of the preputium 
and penis sheath. In some specimens it 
was found to be quite large but very 
asymmetrically developed, so that it pro- 
jected deeply into the preputium on one 
side. The velum lies peripheral to another 
ring of tissue, the sarcobelum, which 
surrounds and closes the outlet of the penis 
sheath; it is small and ill-defined in S. 
montanensis. Internally, the preputium 
has a prominent glandular lining and two 
longitudinal muscular pillars as long as 
the organ or nearly so. One pillar may 
be split, forming an apparent smaller 
third one. A few transverse to diagonal 
folds may pass from pillar to pillar. 
The penis is short and thick and is ex- 
tremely so in its more contracted states. 
Grossly, it is divisible into two successive 
parts, a basal column and a terminal 
"papilla". The latter is tapered and 
elongate -conical and is well set off from 
the preceding part by its lesser diameter. 
It forms about 1/6 to 1/3 of the length of 
the organ. The basal column is very 
thick and firmly muscular, and it is 
widened proximally. The penis shows 
bilateral symmetry; it has a greater and 
a lesser curvature which may be taken 
respectively for dorsal and ventral sides. 
There is a transverse swelling of the 
lesser curvature that represents a muscu- 
lar penial knot, and there is a median 
longitudinal depression on the opposite 
curvature that suggests the presence of a 
"dorsal" lacuna. The knot occurs at the 
junction of the basal column and "papilla" 
of the penis, somewhat distal to the mid- 
length of the organ. In a few specimens, 
where the organ was rather well extended 
and not distorted, the knot was easily 
identified. However, there usually was 
distortion resulting from compression of 
the penis by its sheath. Also, in the con- 
tracted state the knot was often pressed 
tightly backward, against the preceding 
muscular base, so that it was separated 



SUBGENUS HINKLEYIA (LYMNAEIDAE: STAGNICOLA) 



253 



from the latter only by a closed, practically 
indistinguishable cleft. 

Shell size and maturity - For the series 
of S. montanensis studied, it appeared that 
sexual maturity could be rather exactly 
related to shell-length. In several speci- 
mens about 4 mm in shell-length, the 
smallest dissected, all of the genital 
organs were present, but immature, and 
the major glandular structures of both 
male and female systems were especially 
small. In these individuals, the penis was 
a distinct, separate structure which pro- 
jected well into the preputium beyond the 
sheath, which was very short. It was 
evident that the male system leads the 
female system ontogenetic ally, and that 
the penial complex matures first, closely 
followed by the lower prostate. The male 
organs were practically adult in snails 
having a shell 6 mm long, and both genital 
systems were mature in size and ap- 
pearance in those having attained a shell- 
length of nearly 7 mm and over. 

Radula - A single radular membrane, 
from a specimen having a shell 8.1 mm 
long, was examined. The radula was 1.3 
mm long and 0.7 mm wide; it bore an 
estimated 5,500 teeth, which were ar- 
ranged in 96 transverse rows and in about 
60 longitudinal rows. All of the teeth of 
the median row, the centrals, were a- 
nomalous; each was evidently fused with 
the first lateral teeth adjoining it on either 
side. The resulting compound structures 
were extremely broad and irregularly 
multicuspid. There were 5 and 6 normal 
bicuspid laterals on the left and right sides 
respectively, in addition to the anomalous 
first laterals. In the marginal direction, 
the laterals were successively narrower. 
In each transverse row, two tricuspid 
intermediate teeth separated the series of 
lateral and marginal teeth on each side. 
There were many and smaller cusps on the 
marginals except on the first few that 
were transitional to the intermediates in 
each row and except for those that formed 
the last several longitudinal rows along 
the edge of the radula. The last two or 
three teeth in each transverse row were 
minute, simple, rod- shaped elements that 



were faint or obsolete. In the highest 
count obtained for a transverse row, with 
vestigial or incipient teeth included, 20 
teeth were recorded for the left side of the 
radula and 23 were recorded for the right 
side. The number of teeth in particular 
transverse rows could not be determined 
exactly, and showed some irregular vari- 
ation among rows. The transverse count 
given was made in the unworn part of the 
radula, near the posterior end, where the 
counts tended to be higher. The teeth 
closely resembled those figured by F. C. 
Baker (1911, 1938) for many species of 
Stagnicola. 

Morphological comparison oiStagnicola 
montanensis with other species - In 
characters of its soft parts Stagnicola 
montanensis clearly differs from all suf- 
ficiently known lymnaeids except one, S. 
caperata. The author has acquired con- 
siderable anatomical evidence which con- 
firms that S. caperata is allied to, but very 
distinct from, the species of typical Sto^^m- 
cola (Walter, 1961), as contended by F. С 
Baker (1928), who partly relied on some 
of the more obvious anatomical characters 
of S. caperata in erecting the subgenus 
Hinkleyia for the species. Hubendick's 
suggestion that S. caperata and Fossaria 
hum.ilis are synonymous deserves no con- 
sideration. Anatomical characters which 
S. montanensis and S. caperata share with 
the American species of typical Sía^n¿ со Za 
are: a comparatively short, bilaterally 
symmetrical penis, with a knot near its 
midlength; a comparatively robust, com- 
paratively short penis sheath; a prostate 
pouch; and a well-developed vaginal 
sphincter. Among these snails there is 
a general similarity in the conformation 
of the whole genitalia and of the kidney, 
and a characteristic common to them is 
the possession of a series of bicuspid 
lateral radular teeth. These forms, on 
these characters, constitute a well-defined 
natural group among the American 
Lymnaeidae even though the status of the 
genus Stagnicola needs clarification, par- 
ticularly in regard to certain European 
species (see Jackiewicz, 1959). However, 
the nominal subgenus Nasonia, of Stagni- 



254 



TAYLOR, WALTER AND BURCH 



cola, erected for certain American 
species, must be rejected on new evidence. 
A series oi"Stagnicola ÍNasonia)"bulimo- 
ides teckella from Texas was dissected 
and their anatomy proved to be particularly 
similar to, and perhaps identical with, 
that of Fossaria. A radula from this 
series was examined also, and its marginal 
teeth were found to be tricuspid, with long 
daggerlike cusps: a type of dentition that 
is grossly unlike that of Hinkleyia or 
Fossaria, and that is apparently unique in 
Lymnaeidae. None of the lateral teeth 
proved to be unequivocally bicuspid; the 
margins of the two large cusps tended to 
be irregularly serrate, showing some 
fairly pronounced projections that might 
have been counted as additional cusps. The 
teeth appeared to be thin and delicate in 
comparison with that observed by the 
author in the clearly bicuspid laterals of 
various species of Stagnicola. 

The kinship of S. montanensis and S. 
caperata is unquestionable. The charac- 
ters they share, in contradistinction to 
other known species of Stagnicola, are: 
1, a somewhat gradual transition between 
the vaginal sphincter and the musculature 
preceding it; 2, remarkable stoutness of 
the vas deferens; 3, extreme shortness and 
stoutness of the penis; and 4, the placement 
of the knot of the penis somewhat distad 
of the midlength of the organ. The two 
species have other characters in common, 
each of which is parallelled in some other 
lymnaeid, but which together set the two 
species apart from others. These are: 
great thickness of the lower spermathecal 
duct, the shape of the lower prostate and 
its fold (as described above for S. montan- 
ensis), a short and thick penis sheath, and 
an unusually short penial "blade" or 
papilla. Both species, in respect to the 
texture and form of the major glandular 
organs of their female system also tend to 
diverge from other Stagnicola, while 
tending toward Fossaria. Both show 
general similarities in their conformation 
texture, and pigmentation. Also, the foot 
and tentacles of S. caperata are usually 



relatively slender, as was noted for S. 
montanensis. 

The possibility of a close relationship 
of these two species to S. árctica, S. 
vahli, and S. diaphana, was raised on con- 
sideration of the report by Hubendick 
(1951) of an unusually short and stout 
penis in these three forms. However, 
the author (Walter) has examined S. árctica 
from the same area (Moose Factory, 
Hudson's Bay, Ontario, Canada) from 
which Hubendick obtained his material of 
the species, and its penis, like the 
remainder of its anatomy, proved to be 
like that of typical Stagnicola. S. vahli 
and S. diaphana rema.in to be reinvestigated 
in this connection. 

No anatomical differences between S. 
montanensis and S. caperata were surely 
identified, although the penial knot seems 
to be less developed in the former. Any 
minor or subtle differences that exist must 
have been masked by the observed con- 
siderable variation of particular charac- 
ters among individuals. This variation, 
in large part, may not represent ge- 
netically determined characters, but the 
individual specimen's particular immedi- 
ate reaction to the killing process used on 
it, as discussed before. Consequently, 
anatomical differences between S. montan- 
ensis and S. caperata probably are to be 
demonstrated adequately only by study of 
considerably more material of both 
species. Differences might also be re- 
vealed by study of serial sections, by 
observations of the living animals, and by 
further examinations of radulae. The egg 
mass of S. montanensis is not known, but 
it may be particularly similar to that 
of S. caperata, which was found to be 
unique among known lymnaeid egg masses. 
In the S. caperata mass, the egg-capsules 
are nearly spherical and rather small, 
while their individual sets of envelopes are 
more than twice as thick, relatively, as 
those of other Stagnicola. The egg-mass, 
instead of having the common type of thick, 
firm and obviously differentiated outer 
tunic, has a thin one that is hardly visible. 



SUBGENUS HINKLEYIA (LYMNAEIDAE: STAGNICOLA) 



255 



Cytological Study of the Reproductive Cells 
oí Stagnicola (Hinkleyia) montanensis 

Previous cytological studies of Basom- 
matophoran snails include 25 species and 
subspecies of the Lymnaeidae (Table 6). 
Ten of these species and subspecies, all 
with the haploid chromosome number 18, 
belong to the genus Stagnicola (9 to 
Stagnicola s.S., 1 to Hinkleyia). The 
purpose of the present study was to de- 
termine if Stagnicola (flinkleyia) montan- 
ensis had this same characteristic 
chromosome number and whether or not 
other cytological details of spermato- 
genesis were similar to those found in 
other lymnaeids. 

Materials and methods - Fifteen speci- 
mens of Stagnicola (Ц.) montanensis were 
studied cytologically. Six were from Round 
Spring, Gooding Co., Idaho, and 9 from 
Driggs, Teton Co., Idaho. The snails 
were fixed and preserved in Newcomer's 
fluid (Newcomer, 1953). The procedure 
followed was to crack the shells (to allow 
rapid penetration of the fixative) and im- 
mediately drop the snails into the fluid. 
The ovotestes were later removed by 
dissection and stainedby the acetic -orcein 
squash technique (La Cour, 1941). Obser- 
vations were made with a Tiyoda micro- 
scope using a 90x (n. a. 1.25) oil immersion 
objective and 10-30x oculars. The 
chromosomes in Figures 3 and 4 were 
drawn with the aid of a camera lucida 
and reproduced at a table -top magnifi- 
cation of 4650x. Photographs (Figs. 5, 6) 
were taken using a 20x ocular, oil im- 
mersion objective, a Kodak Wratten 57 A 
(green) filter, and Kodak Micro-File film. 

Observations - This material was not 
ideal for cytological studies because none 
of the snails examined were at the peak 
of gametogenesis; they were either imma- 
ture or active gametogenesis had passed. 
However, in all specimens there was 
limited activity of the sex cells and two 
specimens from each locality had enough 
dividing cells to determine the chromo- 
some number of this species. 

The chromosome number of Stagnicola 
montanensis (n=18) is that found for all 



other Stagnicolas which have been in- 
vestigated (Table 6). This number is 
characteristic of lymnaeids, indeed of 
aquatic pulmonate snails in general 
(Burch, 1959; 1960b). The only Lymnae- 
idae with chromosome numbers deviating 
from this basic number are Fossaria 
modicella rustica (n=19), and F. ollula 
pervia. Radix auricularia, R. ovata, and 
R. pereger (n=17) (Table 6). 

In general, details of gametogenesis 
(i.e., chromosome behavior and general 
appearance of the cells) seem to be the 
same as in other lymnaeids. This process 
has been described in detail for Lymnaea 
stagnalis by Perrot (1930) and for Stagni- 
cola emarginata serrata by Burch, 1960b. 
In the male germ line, germinative cells 
lining the acini of the ovotestis go through 
a series of spermatogonial divisions in 
preparation for meiosis. The metaphase 
chromosomes of these cells appear highly 
contracted, and caryotype analysis was not 
possible from this material. Nevertheless, 
the monocentric nature of the chromo- 
somes could still be seen in the "primary 
constrictions", and side views of meta- 
phase -anaphase of the first meiotic di- 
vision clearly confirm this. This is in 
contrast to the chromosomes "en forme 
de bâtonnet ou de boule" described for 
Lymnaea stagnalis by Perrot (1930) and 
the "dot-shaped" ones seen by Inaba and 
Tanaka (1953) in Fossaria ollula pervia 
and Radix japónica, which shape the latter 
authors consider characteristic of aquatic 
pulmonate snails (see also Inaba, 1959). 
Miotic chromosomes similar to those of 
Stagnicola montanensis were reported 
for other basommatophoran snails by 
Burch (1959, 1960a, b). 

Although Perrot (1930) speaks of prima- 
ry, secondary, and tertiary spermato- 
gonial cells in Lymnaea stagnalis, there 
are characteristically six spermatogonial 
divisions in Stagnicola montanensis. This 
number is indicated by the appearance of 
the sperm and spermatids attached to 
nurse cells in clusters of 256. Only rarely 
are there less than six gonial divisions. 
Spermatogonia divide synchronously and 
may be seen in clusters of 4, 8, 16, and 



256 



TAYLOR, WALTER AND BURCH 



TABLE 6. Chromosome numbers in the Lymnaeidae^ 





Hap- 


Dip- 






Species 


loid 
No. 


loid 
No. 




Investigator 




Lymna 


\ea 






L. stagnalis lacustris 


18 


36 


Perrot 


, J.-L., 1930 


L. stagnalis rhodani 


18 


36 


Perrot 


, J.-L., 1930; 1934 


L. stagnalis jugularis 


18 

Stagnier 


ola 


Burch, 


1959; 1960b 


S. palustris 


18 


— 


Perrot and Perrot, 1938; Burch, 1960b 


S. palustris elodes 


18 


36 


Burch, 


1959; 1960b 


S. palustris desidiosa 


18 


36 


Burch, 


1959; 1960b 


S. umbrosa 


18 


— 


Burch, 


1959; 1960b 


S. lancéala 


18 


— 


Burch, 


1960b 


S. reflexa 


18 


— 


Burch, 


1959; 1960b 


S. exilis 


18 


36 


Burch, 


1959; 1960b 


S. catas copium 


18 


— 


Burch, 


1959; 1960b 


S. emarginata serrata 


18 


— 


Burch, 


1959; 1960a, b 


S. caperata 


18 


— 


Burch, 


1959; 1960b 


S. montanensis 


18 


36 


Burch, 


this paper 




Acella 






A. haldemani 


18 


36 


Burch, 


1959; 1960b 




Pseudosuccinea 






P. columella 


18 


36 


Burch, 


1959; 1960b 




BuUmnea 






В. megasoma 


18 


36 


Burch, 


1959; 1960a, b 




Fossaria 






F. ollula pervia 


17 


34 


Inaba and Tanaka, 1953 


F. parva 


18 


— 


Burch, 


1959; 1960b 


F. modicella 


18 


36 


Burch, 


1959; 1960b 


F. modicella rustica 


19 
Radix 




Burch, 


1959; 1960b 


R. auricularia 


17 


_.- 


Perrot and Perrot, 1938 


R. ovata 


17 


— 


Perrot and Perrot, 1938 


R. pereger 


17 


— 


Perrot and Perrot, 1938 




-- 


34 


Burch, 


1960b 


R. limosa 


18 


— 


Le Calvez and Certain, 1950 


R. japónica 


18 


36 


Inaba, 


1950; Inaba and Tanaka, 1953 



9 Chromosome numbers reported by Linville (1900), Crabb (1927), Archie (1942), 
Bretschneider (1948), et al., are not listed because they are either in error or not 
reliable. 



SUBGENUS Я/JV^Lí;r/A (LYMNAEIDAE: STAGNICOLA) 



257 



4SÍ 






FIGS. 3, 4. Chromosomes of Stagnicola 

montanensis 2770x. 

FIG. 3. Metaphase bivalents of the first 

meiotic division of spermatogenesis (polar 

view). 

FIG. 4. Late prophase chromosomes of a 

gonial cell. 

32 cells. All cells of any particular 
cluster are always in exactly the same 
stage of division. Primary spermatocytes 
are found in clusters of 64 and the 
secondary spermatocytes in clusters of 
128. Similar conditions have been seen 
in other lymnaeids (Burch, 1960b). 

The shape, appearance, and behavior of 
the meiotic metaphase chromosomes are 






in general as in other lymnaeids. In 
polar view they may be seen as small 
ovals or rods, but more often as "tetrads" 
(Fig. 3). The chromosomes are often 
difficult to count at this stage because some 
tend to separate before others, and often 
this early separation begins before all the 
chromosomes have been brought to lie 
in one plane. The chromosomes can be 
counted most readily and accurately during 
late diakinesis and prometaphase of the 
first meiotic division. All four speci- 
mens from which counts could be made 
had 18 bivalents present during late 
prophase and metaphase of the first mei- 
otic division of spermatogenesis. The 
pairing behavior of the bivalents appeared 
to be normal, and during diakinesis the 
paired chromosomes were held together 
by one or more chiasmata. Thirty-six 
chromosomes were present in gonial di- 
visions (Fig. 4). 

The most striking feature in gameto - 
genesis of this species compared to other 
lymnaeids is the presence of five to seven 
large chromatin bodies in early prophase 
nuclei of the first meiotic division of 
spermatogenesis (Figs. 5 and 6). These 
bodies were present in all specimens ex- 






FIGS. 5, 6. Cells of Stagnicola montanensis in spermatogenesis, 1370x. 

FIG. 5. Early first meiotic prophase of spermatogenesis with six visible deep-staining 

chromatin bodies. 

FIG. 6. Cells at pachytene or early diplotene stage of spermatogenesis. 



258 



TAYLOR, WALTER AND BURCH 



amined, from both localities. Sometimes 
they appear vesicular. Similar structures 
have not been reported previously in 
lymnaeid snails, but they have been seen 
by Burch (unpublished) in Stagnicola 
caperafa. Perhaps they are similar in 
nature to those seen by Husted and Burch 
(1953) in the polygyrid land sna.il Allogona 
profunda. Although these chromatin 
bodies might suggest either the presence 
of supernumerary chromosomes or that 
the snail is polyploid, obviously neither is 
the case. The exact nature of these bodies 
in relation to the chromosomes and the 
nuclear cycle remains to be determined. 
In any event they are perhaps another 
character linking Stagnicola caperata and 
S. montanensis . 

Distribution of Stagnicola montanensis 

Recent occurrences of Stagnicola 
montanensis - This species is widespread 
in the eastern Columbia and northern Great 
Basin drainages in the western United 
States (see Fig. 7). Most specimens were 
collected alive, but a few were recently 
dead. 

The locality information given for U. S. 
National Museum shells collected by Hall, 
Hoffman, and Sinitsin is all that is on the 
labels; in some cases it is not precise. 
The original data accompanying the speci- 
mens were destroyed several years ago. 

In the following list of localities, the 
number of specimens is in parentheses 
after the citation oí institution^ and cata- 
logue numbers. Localities are listed 
from west to east and north to south. 

MONTANA. Ravalli Co.: Hays Creek 
near Ward (probably about S 1/2, sec. 3, 
T. 4 N., R. 21 W.). L. E. Daniels, April 
25, 1912; UMMZ 76196 (type series, 35), 
27799 (6), USNM 570589 (1 figured speci- 



men), 570929 (4); Junius Henderson, June 

26, 1915; USNM 570590 (11). 

IDAHO. Gooding Co.: SE 1/4 sec. 1, 
T. 3 S., R. 13 E. Unnamed tributary of 
Catchall Creek by house in southwest 
corner of Bowman Flat. D. W. Taylor, 
July 26, 1959; USNM 633926 (14). SW 1/4 
sec. 4, T. 3 S., R. 14 E. Round Spring 
(PI. 5, Fig. 2). D. W. Taylor, July 26, 
1959; USNM 633927 (about 200). 

Twin Falls Co.: Center of sec. 28, T. 
14 S., R. 18 E. South Fork of Shoshone 
Creek at road crossing 0.55 mile north 
of junction of roads to Fawn Spring and 
Cottonwood Creek. D. W. Taylor, Sept. 
2, 1957; USNM 633928 (1). NE 1/4 sec. 

27, T. 14 S., R. 18 E. Seepy area beside 
road to Fawn Spring 1.05 miles northeast 
of junction with road to Shoshone Creek. 

D. W. Taylor, Sept. 1, 1955; USNM 633929 
(3). SW l/4SWl/4sec.27,T. 14 S., R. 18 

E. Head of tributary of South Fork of Sho- 
shone Creek beside road at junction of 
road to Fawn Spring and road to Shoshone 
Creek. D. W. Taylor, Sept. 1, 1955; 
USNM 633882 (1, figured specimen), USNM 

633883 (2, figured specimens), USNM 

633884 (28). Near center of south edge 
of sec. 3, T. 15 S., R. 18 E. Cottonwood 
Creek. D. W. Taylor, Sept. 1, 1955: 
USNM 633885 (2, figured specimens), 
USNM 633886 (60). Southeast corner of 
SW 1/4 sec. 4, T. 16 S., R. 18 E. SmaU 
trickle of water in wash 0.1 mile north of 
quarter corner. D. W. Taylor, Sept. 2, 
1955; USNM 633930 (71). 

Franklin Co.: Leslie Wright's ranch, 
30 miles south of Soda Springs (according 
to local inquiry this locality is in the W 1/2 
sec. 7, T. 12 S., R. 41 E). L. Sinitsin, 
Sept. 12, 1929; USNM 530919 (12). NW 1/4 
sec. 33, T. 12 S., R. 40 E. Spring on 
south side of Cottonwood Creek. D. W. 
Taylor, R. С Bright, Sept. 10, 14, 1959; 



10 



CAS = California Academy of Science, San Francisco, California. 
UCMNH = University of Colorado Museum of Natural History, Boulder, Colorado. 
UMMZ = Museum of Zoology, University of Michigan, Ann Arbor, Michigan. 
USGS = U. S. Geological Survey, Washington D. С 
USNM = U. S. National Museum, Washington D. C. 



SUBGENUS HINKLEYIA (LYMNAEIDAE: STAGNICOLA) 



259 



119 



117 



115'^ 



113^■ 



lll^' 




EXPLANATION 
■ Sfagnicola pilsbryi (Hemphill) 
• Recent S. montanensis (Baker) 
A Fossil 5 montanensis (Baker) 



100 200 

f- SCALE 

J. — 1^' .'' 



\ NX 



FIG. 7. Map showing distribution of Stagnicola pilsbryi (Hemphill) and S. montanensis 
(Baker) in the U. S. A. Precise locality data are given in the text. 



260 



TAYLOR, WALTER AND BURCH 



USNM 633933 (67). 

Bear Lake Co.: Pearl Cr., NW 1/4 sec. 
30, T. 10 S., R. 43 E. D. W. Taylor, R. С 
Bright, Aug. 29, 1961; USNM 633920 (2). 
Unnamed tributary of Stauffer Creek, NW 
1/4 SW 1/4 sec. 5, T. 12 S., R. 43 E. 
D. W. Taylor, R. С Bright, Aug. 29, 1961; 
USNM 633921 (48). Emigration Canyon, 
W 1/2 NE 1/4 sec. 23, T. 12 S., R. 42 E. 
D. W. Taylor, R. С Bright, Aug. 29, 1961; 
USNM 633922 (66). 

Teton Co.: Center of sec. 35, T. 6 N., 
R. 45 E. Ditches beside state highway. 
D. W. Taylor, J. D. Love, J. de la 
Montagne, Aug. 28, 1959; USNM 633931 
(about 150). SE 1/4 NW 1/4 sec. 35, T. 
5 N., R. 45 E. Ditch and small stream on 
west side of state highway at south edge 
of Driggs. D. W. Taylor, J. D. Love, J. 
de la Montagne, Aug. 28, 1959; USNM 
633932 (about 125). Four miles west of 
Victor. Muddy stream, Henry Drake's 
ranch. L. Sinitsin, Sept. 15, 1929; USNM 
530998 (22). Four miles southwest of 
Victor. Half-dry ditch, Blanchard' s ranch. 
L. Sinitsin, Sept. 15, 1929; USNM 531179 
(10), 530997 (24). 

WYOMING. Lincoln Co. : Pasture at Bed- 
ford. W. H. Krull, May 28, 1941; USNM 
536403 (13). Grassland at Grover. W. 
H. Krull, May 29, 1941; USNM 536407 
(about 100). Pasture at Grover. W. H. 
Krull, May 30, 1941; USNM 536416 (78). 
Near Afton. W. H. KruU, Sept. 15, 1941; 
USNM 536460 (16). Meadows and pastures 
in the region of Afton. W. H. Krull; 
USNM 522817 (45). 

UTAH. Cache Co.: Between Logan and 
Smithfield. Muddy ditch across a swampy 
pasture by the road. L. Sinitsin, Sept. 24, 
1929; USNM 531309 (1). Spring at north 
side NW 1/4 NW 1/4 sec. 23, T. 14 N., R. 
3 E., tributary to Beaver Creek. D. W. 
Taylor, Aug. 27, 1961; USNM 633923 (59). 

Summit Co.: Small stream 2 miles 
northwest of Kimballs. Leslie Hubricht, 
1938; UMMZ 176539 (4). Head of East 



Canyon, 22 miles east of Salt Lake City. 
Half-dry spots by a ditch. L. Sinitsin and 
others, Sept. 26, 1929; USNM 530921 (9). 
Head of East Canyon, 25 miles east of 
Salt Lake City. Swampy pasture, Mr. 
McPolim's ranch. L. Sinitsin and others, 
Sept. 26, 1929; USNM 530922 (7). Head of 
East Canyon, 25 miles east of Salt Lake 
City. Swampy pasture along a ditch at 
Mr. McPolim's ranch. L. and D. Sinitsin, 
Sept. 26, 1929; USNM 531477 (6). Head of 
East Canyon, 27 miles east of Salt Lake 
City. Swampy pasture, Mr. Pace's ranch. 
L. Sinitsin and others, Sept. 26, 1929; 
USNM 530923 (9). Creek at Park City. 
L. Sinitsin, Oct. 1, 1929; USNM 530912 (7). 

Beaver Co.: Low's ranch, Beaver. Hall 
and Hoffman, Sept. 24, 1929; USNM 530914 
(6). 

NEVADA. Nye Co.: Springs 2 miles 

southeast of MiUett P. O. May, 1931; CAS 

29060 (2). 

11 
Fossil occurrences^ of Stagmcola 

montanensis . 

PLIOCENE. Teewinot Formation, Teton 
County, Wyo.: locality^ 19105. USNM 
563097 (1), USGS (62). 

LATE PLEISTOCENE. American FaUs 
Lake Beds, Power County, Idaho: locality 
19169. UMMZ uncat. (8). 

Older alluvium, Power County, Idaho: 
locality 20474. USGS (9). 

Unknown unit. Power County, Idaho: 
locality 20477. USGS (6). 

Unnamed unit, Bannock County, Idaho: 
locality 22328. USGS (about 400). Locality 
22410. USGS (9). 

Deposits of Lake Thatcher, Caribou and 
Franklin counties, Idaho: Locality ?21143, 
USGS (1). Locality 22396. USGS (25). 
Locality 23066. USGS (1). 

Unnamed unit, Bear Lake County, Idaho: 
locality 21062. USGS (7). 

Provo Formation, Franklin County, 
Idaho: locality 22395. USGS (21). 



11 



Precise geographic and geologic information on the localities is given in the Appendix, 
P 270. 



SUBGENUS HINKLEYIA (LYMNAEIDAE: STAGNICOLA) 



261 



Stagnicola iflinkleyia) caperata (Say), 1829 
PI. II, Fig. 2-12 



Galba caperata (Say): Baker, 1911, 
Chicago Acad. Sei. Spec. Pub. 3: 225, PI. 
28, Fig. 20-33; PI. 29, Fig. 1-3. 

Stagnicola caperata (Say): Baker, 1928, 
Wisconsin Geol. Nat. Surv. Bull. 70(1): 
260, PI. 18, Fig. 43-47. 



This species is accepted in the sense of 
F. C. Baker (1911,1928), andnodiscussion 
of variation or synonymy is necessary. 
Some descriptive and diagnostic detail on 
the shell is given in the section on Stagni- 
cola montanensis under "Comparisons 
of shells" p 241; anatomical details and 
a description of the egg masses can be 
found under "Morphological comparison 
of Stagnicola montanensis with other spe- 
cies* on p 253. 

Ecologie information for S. caperata 
east of the Rocky Mountains is available 
through the references cited above; the 
habitats of S. caperata in the Snake River 
and Great Basin drainages are discussed 
on p 267-270. 

The oldest known geologic occurrence of 
S. caperata is middle Pliocene. Specific 
locality data and the evidence for the age 
assignment are given by Taylor (1960). 

The geographic distribution of S. caper- 
ata is from "Quebec and Massachusetts 
west to California; Yukon Territory and 
James Bay south to Maryland, Indiana, 
Colorado and California" (Baker, 1928). 
The following specific locality records are 
for the eastern Columbia River drainage 
and northern Great Basin only (compare 
with Fig. 8). They are intended to docu- 
ment the relative abundance and distri- 
bution of Stagnicola caperata and include 
both published and unpublished oc- 
currences. 

Recent occurrences of Stagnicola 
caperata. 

MONTANA. Flathead Co.: no specific 
locality. L. E. Swanson; USNM 468507. 

IDAHO. Washington Co.: Pool 2 mi. 
SE of Weiser. Junius Henderson and E. 
H. Nanney, June 22, 1927; UCMNH 15205, 



USNM 570483. 

Canyon Co.: Indian Creek near Caldwell. 
H. M. Tucker; UCMNH 16354 in part. 

Elmore Co.: NE 1/4 sec. 12, T. 5 S., 
R. 10 E., and NW 1/4 sec. 7, T. 5 S., R. 
HE. Irrigation ditch on common section 
line. D. W. Taylor, Aug. 8, 1959; USNM 
633934. NW 1/4 sec. 8, T. 5 S., R. 11 
E. Irrigation over-flow. D. W. Taylor, 
Aug. 8, 1959; USNM 633935. 

Gooding Co.: Dry Creek, center E side 
sec. 15, T. 5 S., R. 14 E. D. W. Taylor, 
July 18, 1959; USNM 633936. 

Twin Falls Co.: Salmon Falls Creek, 
SW 1/4 NE 1/4 sec. 30, T. 8 S., R. 14 E. 
D. W. Taylor, July 30, 1955; USNM 633937. 
Salmon River near Twin Falls (probably 
same locality as preceding). L. Sinitsin, 
Sept. 7, 1929; USNM 530983. Deep Creek, 
NW 1/4 NWl/4 sec. 7, T. 11 S., R. 14 E. 
D. W. Taylor, Aug. 28, 1955; USNM 633938. 

Power Co.: Snake River, NE 1/4 sec. 
12, T. 9 S., R. 29 E. D. W. Taylor, Sept. 
3, 1961; USNM 633924. 

Clark Co.: North of Dubois on the road 
to Dillon, Montana. L. Sinitsin, Sept. 17, 
1929; USNM 531442. 

Jefferson Co.: Ditch beside highway 15 
miles south of Dubois. L. Sinitsin, Sept. 
16, 1929; USNM 531377. 

Bannock Co.: Bridge west of Pocatello 
(probably Portneuf River). Junius 
Henderson and E. H. Nanney, June 20, 1927; 
UCMNH 15192, USNM 570452. Wet pasture 
near Lava Hot Springs. L. Sinitsin, Sept. 

11, 1929; USNM 531400. 

Caribou Co.: Brook near reservoir 2 
or 3 miles west of Soda Springs. Junius 
and B. R. Henderson, July 23, 1930; 
UCMNH 17430, USNM 570453. Swenson's 
ranch, 25 miles south of Soda Springs. 
(From local inquiry this locality is near 
the common corner of sees. 17, 18, 19, 
20, T. 11 S., R. 41 E). L. Sinitsin, Sept. 

12, 1929; USNM 530916, 531387. Mee- 
cham's ranch, 25 miles south of Soda 
Springs. (From local inquiry this locality 
is in the NW 1/4 sec. 20, T. 11 S., R. 41 
E.). L. Sinitsin, Sept. 12, 1929; USNM 
530917, 531335, 531340. 

Franklin Co.: P. Andersen's ranch, 
30 miles south of Soda Springs. (From 



262 



TAYLOR, WALTER AND BURCH 
PLATE II 




SUBGENUS HINKLEYIA (LYMNAEIDAE: STAGNICOLA) 



263 




EXPLANATION 

• Recent Slagnicola coperata (Soy) 

* Fossil S coperata (Say) 



FIG. 8. Map showing distribution of Stagnicola caperata (Say) in the eastern Columbia River and northern 
Great Basin drainages. Precise locality data are given in the text. 



PLATE U 

FIG. 1. Stagnicola pilsbryi. "Fish Spring, Nevada". Probably Fish Springs, Juab Co., Utah. Length 7.9 
mm, 61/4 whorls. Type. ANSP Ö2293. 

FIGS. 2, 3. S. caperata. Logan, Cache Co., Utah. Length 8.0 mm, 5 1/4 whorls. USNM 522635c. 

FIGS. 4, 5. S. caperata. Same locality. Length 9.0 mm, 5 3/4 whorls. USNM 522635a. 

FIGS. 6, 7. S. caperata. Same locality. Length 8.0 mm, 5 1/4 whorls. USNM 522635b. 

FIGS. 8, 9. S. caperata. Meecham's ranch, NW 1/4 sec. 20, T. 11 S., R. 41 E., Caribou Co., Idaho. Length 
7.3 mm, 4 3/4 whorls. USNM 531335c. 

FIG. 10. S. caperata. Same locality. Length 11.1 mm, 5 3/4 whorls. USNM 531335a. 

FIGS. 11, 12. S. caperata. Same locality. Length 8.6 mm, 4 3/4 whorls. USNM 531335b. 



264 



TAYLOR, WALTER AND BURCH 



local inquiry this locality is probably in 
the E 1/2 sec. 7, T. 12 S., R. 41 E.). 
L. Sinitsin, Sept. 12, 1929; USNM 530918, 
531353. Leslie Wright's ranch, 30 miles 
south of Soda Springs. (From local inquiry 
this locality is in the center of the W 1/2 
sec. 7, T. 12 S., R. 41 E.). L. Sinitsin, 
Sept. 12, 1929; USNM 530920, 531430. 
NW 1/4 NW 1/4 sec. 20, T. 15 S., R. 39 
E. Roadside ditch. D. W. Taylor, R. С 
Bright, Sept. 11, 1959; USNM 633939. 

Bear Lake Co.: Rivulet along auto road 
17 miles northwest of Montpelier. Junius 
Henderson and F.E. Swisher, July 27, 1921 ; 
UCMNH 11792, USNM 570451. Pasture, 
Liberty. W. H. Krull, June 6, 1941; USNM 
536427. Pasture, Ovid. W. H. Krull, June 
6, 1941; USNM 536434. Meadow, Paris. 
W.H. Krull, May 22, 1941; USNM 536365. 
Pasture, Paris. W.H. Krull, May 22, 1941; 
USNM 536371. Roadside ditch 2 miles north 
of Montpelier. Junius Henderson and F. E. 
Swisher, July 27, 1921; UCMNH 11788. 

WYOMING. Teton Co.: Center sec. 20, 
T. 40 N., R. 116 W. Flat Creek at road. 
D. W. Taylor, Sept. 2, 4, 1959; USNM 
633940. 

Sublette Co.: Dry hollow in floor of Dell 
Creek valley about one mile above mouth 
of creek, SW 1/4 sec. 21, T. 38 N., R. 113 
W. D. W. Taylor, Aug. 7, 1950; UMMZ 
178185. Wet moss and grass flat in floor 
of Dell Creek valley about one mile above 
mouth of creek, SW 1/4 sec. 21, T. 38 N., 
R. 113 W. D. W. Taylor, Aug. 8, 1950; 
UMMZ 178198. Small stream just north 
of Faris ranch house, NW 1/4 sec. 28, 
T. 38 N., R. 113 W. D.W. Taylor, Aug. 
9, 1950; USNM 633941. Dell Creek, center 
N 1/2 NE 1/4 sec. 29, T.38N., R. 113W., 
D.W. Taylor,Aug. 12, 1961; USNM 633925. 

Uinta Co.: Small creek where highway 
89 crosses Bear River. Honess, July 16, 
1953; USNM 633942. SmaU stream tribu- 
tary to Bear River on Jamison Ranch 
(lower ranch), 7 miles S of Evanston on 
highway 89. Honess, July 16, 1953; USNM 
633943. 

UTAH. Box Elder Co.: Adney farm, 
Corinne. W. H. KruU; USNM 513888. 
Sloughs at Bear River Bay bird sanctuary, 
west of Brigham. S. S. Berry, Sept. 3, 



1934; USNM 633944. 

Cache Co.: Swamp, Richmond. W. H. 
Krull, Mar. 31, 1941; USNM 536402. Near 
Bear River, Benson Ward. W. H. Krull, 
May 6, 1942; USNM 536465. Between 
Logan and Smithfield. L, Sinitsin, Sept. 
24, 1929; USNM 633945. Logan. W. H. 
Krull, Feb. 20, 1939; USNM 522624. 
Wennergren pasture 1, Logan. W.H. Krull, 
Mar. 1, 1940; USNM 522629. Wennergren 
far pasture, Logan. W. H. Krull; Apr. 10, 
1940; USNM 522632. Reese pasture, 
Logan. W. H. Krull, Apr. 10, 1940; 
USNM 522635. 

Rich Co.: Slough on west side of Bear 
River valley about 10 miles west of Sage. 
Junius Henderson; USNM 570464. 

Weber Co.: Pond at head of "Confusin' 
Canyon", SW 1/4 sec. 21 T. 5 N., R. 1 W. 
4700 ft. elev. J. H. Feth, Sept. 1954; USNM 
633947. 

Salt Lake Co.: Small slough on 4th 
South, 11th West, near Jordan River, Salt 
Lake City. Treganza; USNM 199399. Salt 
Lake City. L. E. Swanson; USNM 424332, 
424333. Salt Lake City. F. A. Sampson; 
USNM 570466. Near Salt Lake City. 
Henry HemphiU; UMMZ 73688. Salt Lake 
City. UMMZ 142927. Southeast of Murray; 
L. A. Giddings, 1921; UCMNH 10571. 

Summit Co.: Creek at Park City. L. 
Sinitsin, Oct. 1, 1929; USNM 633946. 

Tooele Co.: No specific locality. A. 
G. Ruthven, 1930; UMMZ 49783. 

Utah Co.: Slough south of Lehi. Junius 
and B. R. Henderson, July 15, 1930; 
UCMNH 17373, USNM 570463. 

Beaver Co.: Low's ranch, Beaver. Hall 
and Hoffman, Sept. 24, 1929; USNM 530913. 
Beaver. L. E. Swanson, Sept. 22, 1934; 
USNM 539047. Beaver. L. E. Swanson, 
Oct. 8, 1934; USNM 539048, Beaver. L. 
E. Swanson, Nov. 21, 1934; USNM 539049. 
Small spring slough at south edge of 
Beaver. Junius and B. R. Henderson, 
July 8, 1930; UCMNH 17334. 

NEVADA. Elko Co.: Pools of Humboldt 
River vaUey. Helen Gaige, 1912; UMMZ 
67590. Humboldt River. Crystal 

Thompson, 1912; UMMZ 5490, 5491, UC 
MNH 17121. 

Nye Co.: Discharge of warm spring, 



SUBGENUS HINKLEYIA (LYMNAEIDAE: STAGNICOLA) 



265 



Monitor Valley. UMMZ 132552. 

Fossil occurrences^^ of Stagnicola 
caper ata 



MIDDLE PLEISTOCENE. Unnamed 
formation, southwestern Idaho. Owyhee 
Co.: localities! 2 20404, 20472. Elmore 
Co.; localities 20105, 20107, 20109, 20112, 
20120. Twin Falls Co.: localities 19219, 
19222, 19225, 20410. 

Raft formation. Power Co., Idaho: 
Locality 20478. 

LATE PLEISTOCENE. American Falls 
Lake Beds, Power Co., Idaho: locality 
21643. 

American Falls Lake Beds or Michaud 
Gravel, Power Co., Idaho: locality 21057. 

Older alluvium or Aberdeen terrace 
deposits, Power Co., Idaho: locality 21636. 

Unknown unit, Bingham Co., Idaho: 
locality 20479. 

Sunbeam Formation?, Power Co., Idaho: 
locality 22332. 

Unnamed alluvium. Twin Falls Co., 
Idaho: locality 20413. 

Deposits of Lake Thatcher, Caribou Co., 
Idaho: localities ?23025, 23027, 23033, 
23037, 23061, 23066. 

Unnamed unit, Bear Lake Co., Idaho: 
locality 22429. 

Lake Bonneville deposit. Caribou Co., 
Idaho: locality 23069. 

Unnamed unit. Box Elder Co., Utah: 
locality 22359. 

Saltair core, Salt Lake Co., Utah: 
localities 21112, 21120, 21122, 21124. 

Unknown unit, Humboldt Co., Nevada: 
locality 19192. 

Stagnicola (flinkleyia) pilsbr'yi (Uem^phill), 
1890 

PI II, Fig. 1 

LeptoUmnea, n, sp.?: Cooper, 1872, 
California Acad. Sei. Proc, ser. 1,4: 172. 

Limnaea [LeptoUmnea) Pilsbryi Hemp- 
hill, 1890, Nautilus 4: 25. 

Galba pilsbryi (Hemphill): Baker, 1911, 
Chicago Acad. Sei. Spec. Publ. 3: 254, 
PI. 4, Fig. A,B. 



Shell of Stagnicola pilsbryi 

Diagnosis - A species of Hinkleyia with 
slightly shouldered whorls whose greatest 
width lies above their middle, a narrow 
tapering spire, small aperture, and dull 
shell surface. Spiral sculpture consists 
of weak, fine, irregular incised lines. 
Axial sculpture is of fine to moderately 
coarse irregular growth lines. 

Type - Academy of Natural Sciences 
of Philadelphia 62293. «Fish Spring, 
Nevada" is the only locality data given by 
Hemphill. Baker(191 l)identified this more 
precisely as being in Nye County, in ap- 
proximately lat. 38o 45 ft. N., Ибо 30 ft. 
W. Hemphill's label with the type says 
"Fish Spring Nevada between Austin and 
Salt Lake", thus ruling out the locality 
specified by Baker. Most probably Hemp- 
hill collected at Fish Springs, northern 
Juab County, Utah (see map, Fig. 7). 

Description of shell - Shell turriform. 
Whorls 6 1/4, separated by a constricted 
suture. Nuclear whorl relatively large, 
as in Stagnicola caperata. The greatest 
width of the last three whorls is above 
their middle, so that they tend to become 
shouldered and slightly flattened peripher- 
ally. Aperture relatively small, one -third 
of total shell length, slightly oblique. 
Both inner and outer lips in the type are 
broken, as shown in the drawing. Colum- 
ella with only a slight trace of fold. К 
unbroken, the shell would not be as 
umbilicate as illustrated, but with a 
narrow perforation. Axial sculpture of 
fine to moderately coarse, irregular 
growth lines slightly retractive to the base. 
Spiral sculpture of weak, fine, irregular 
incised lines; on the body whorl these are 
evident on the posterior part only. 

Length of type 7.9 mm, width 3.3, length 
of aperture 2.6, width of aperture 1.7, 
whorls 6 1/4. 

Remarks - Only three specimens of this 
species are known, all from the original 



12precise geographic and geologic information on the localities is given in the Appendix, 
P 270. 



266 



TAYLOR, WALTER AND BURCH 



lot collected by Henry Hemphill in 1868. 
The two immature specimens are less than 
half the length of the type. They agree 
with the type in size of nuclear whorls, 
shape, and axial sculpture but lack spiral 
sculpture. The bleached periostracum and 
the dirt inside the aperture shows that all 
three were collected as empty shells. 
Hemphill's label notes "These are the best 
I can do for you. I have but two or three 
others the largest more globose than 
these". These additional specimens have 
not been traced. 

The relatively coarse growth lines, 
small size, narrow shape, small aperture, 
and shouldered whorls of this species are 
all characters much like those of Fossaria. 
It is not surprising that Baker (1911), 
Hannibal (1912, p 144) and Hubendick (1951, 
p 199) have grouped Stagnicola pilsbryi 
with species of Fossaria. Nevertheless 
the relatively large nuclear whorl and 
spiral sculpture bar pilsbryi from 
Fossaria and ally it with Stagnicola 
caperata (Say) andS. moniane^sis (Baker). 

Stagnicola pilsbryi differs from S. 
montanensis in sculpture, rate of whorl 
increase and form. The growth lines are 
coarser, so that the shell surface is dull 
rather than shiny. The spiral sculpture 
consists of incised lines, rather than 
series of tiny arcuate lines. The whorls 
enlarge more slowly, so that the body 
whorl of S. pilsbryi is relatively smaller 
than in S. montanensis and the shell as 
a whole is smaller than shells of S. 
montanensis with the same number of 
whorls. The last whorls of S. pilsbryi 
are shouldered, whereas in S. monianensfs 
they are regularly convex. 

In making these comparisons only one 
adult specimen of S. pilsbryi is available, 
and hence no allowance for range of 
variation has been made. Several hundred 
'specimens of S. montanensis have been 
examined, however, and their range of 
variation in several characters does not 
overlap the type of S. pilsbryi. 

Original description - "Shell elongated, 
narrow, somewhat solid, smooth, of a 
light horn-color; consisting of about six 
roundly-shouldered whorls, the last 



flattened on its sides and occupying a 
little more than half the length of the 
shell; lines of growth very delicate, suture 
deep; aperture oval, longer than wide, 
outer lip acute; inner lip subreflexed. 

Length 3/8, breadth 1/8 of an inch. 

Habitat: Fish Spring, Nevada. 

I collected a few specimens of this 
interesting shell in the month of June, 
1868, at this locality, after a long and 
hard day's ride of 40 miles horseback. 
Another long ride next day of 50 miles to 
water, compelled an early start and thus 
the opportunity to secure more specimens 
was lost." (Hemphill, 1890, p 25-26). 

DISTRIBUTION 
AND HABITATS 

Stagnicola pilsbryi is known only living, 
but both S. caperata and S. montanensis 
are known from Pliocene deposits. The 
earliest record of S. montanensis and of 
S. caperata is middle Pliocene, but from 
the fact that they appear essentially 
modern at that time the geologic age of 
the species is probably somewhat greater. 
Within the area of the maps (Figs. 7, 8) 
there is no evidence of major changes of 
distribution. All of the fossil and recent 
occurrences of each species represent 
the same pattern of distribution. 

The three recognized species of 
Hinkleyia have successively larger 
ranges, (see maps, Figs. 7, 8), so that the 
area of distribution of one is enclosed by 
that of another. Stagnicola pilsbryi is 
known only from a single locality in 
western Utah. S. montanensis is found in 
the northern Great Basin and southeastern 
Columbia River drainages. S. caperatais 
widespread in northern North America. 

A list of localities and a description of 
habitats of the species of Stagnicola 
{Hinkleyia) have some value in themselves 
in recording what is known about the 
species. The information available does 
not suffice to answer questions about 
differentiation of the species oí Hinkleyia,^ 
their isolating mechanisms or general 
distribution, but it does suggest directions 
of future study. 



SVBGE^US HINKLEYIA (LYMNAEIDAE: STAGNICOLA) 



267 



Habitats 

Nothing is known of the habitat of 
Stagnicola pilsbryi. From the fact that 
it is a narrowly localized species, where- 
as its close relatives are widespread, one 
might infer it has some ecological special- 
ization. 

Stagnicola caperata is found most often 
in seasonal bodies of water. It is charac- 
teristic of such habitats as irrigation 
ditches, sloughs and shallow ponds. Its 
wide distribution is correlated with its 
tolerance for environments in which few 
other snails live, and with the common 
and widespread occurrence of habitable 
situations. As aquatic snails go, it is 
one not readily subject to geographic 
isolation. 

Stagnicola montanensis is unique among 
North American Lymnaeidae in its habitat. 
It is a pure-water snail, living in the out- 
flow of springs, or in clear mountain 
streams. It is never found in seasonal 
ponds, or stagnant or muddy water bodies, 
but it is never in large clear waters such as 
lakes and rivers. Most Lymnaeidae of 
clean water bodies live in large perennial 
rivers and lakes {Stagnicola (s.s.) emar- 
ginata group, Bulimnea, Acella). Other 
Lymnaeidae living in shallow marginal 
situations are usually found in ponds, 
ditches, sloughs, or swamps without evident 
regard for muddiness or the presence or 
lack of current. Their occurrence is more 
probably correlated with length of growing 
season and the vegetations. S. montanensis 
is unique in combining a pure-water habitat 
with a small or even seasonal water body. 

At several localities S.montonensis was 
notably concentrated in the deeper parts of 
the shallow pools it lived in. Possibly this 
reflects a physiological specialization for 
breathing by means of a gas bubble in the 
lung, or by cutaneous respiration, rather 
than directly inhaling air. Even if these 
colonies were in fact breathing while sub- 
merged, they need not be characteristic of 
the species. Hunter (1953) found different 
states of respiratory behavior within 
different populations oihoth Radix pereger 
and Physa fontinalis in Loch Lomond, 



Scotland. 

Biogeography - Certain details of the 
distribution of Stagnicola montanensis and 
S. caperata are simply and adequately 
explained by their different habitats. In 
the Snake River drainage in south-central 
Idaho, and in the Bear River drainage in 
southeastern Idaho, S. montanensis is an 
upland species and S. caperata is a low- 
land form. This local distribution is 
evidently related to the differences in 
water bodies of the mountains and low- 
lands. 

Nevertheless not all of the differences 
in distribution between S. caperata and 
S. montanensis can be explained ecolo- 
gically. The restriction of S. montanensis 
to the Great Basin and Columbia River 
drainages is the most obvious case. Any- 
one with field experience in the Green 
River, and upper Mississippi River 
drainages as well, finds it hard to believe 
there is any sharp écologie difference 
which would prevent species of the western 
drainages from inhabiting the eastern. 

In lesser details too the distributions of 
these two species seem to be influenced 
by non-ecologic factors. Only S. montan- 
ensis has been found in the Teton River 
and Salt River drainages. Only S. caperata 
has been found living in the upper Snake 
River and Bear River drainages in 
Wyoming, although S. montanensis is 
known fossil from Jackson Hole. 

These apparently non-ecological factors 
of distribution are probably biogeographic. 
This is to say that they are the result of 
the biologic and geologic history of the 
region, and that they reflect past events 
instead of present differences between the 
two species. 

If these details of distribution are cor- 
rectly interpreted as biogeographic, then 
there are significant differences in faunal 
history between the Green River, and the 
Snake River and Bear River; and between 
the upper Snake and Bear Rivers of western 
Wyoming and the more western parts of 
these drainages. These differences may 
be expected in other groups of aquatic 
animals. As knowledge of late Cenozic 
geologic history in this region becomes 



268 



TAYLOR, WALTER AND BURCH 



more detailed, then one may expect to find 
differences also in physical history of the 
basins mentioned. 

Another implication of the historical 
control of such details of distribution is 
that dispersal (active or passive) in these 
species is very slow. Even though these 
snails live in swampy situations, springs 
and ponds, in shallow water bodies, they 
are not effectively carried by birds. One 
can readily understand how snails or clams 
restricted to larger lakes and streams are 
limited to dispersal through their habitat; 
such seems to be the case also with 
Stagnicola montanensis and S. caperata. 

Description of habitats in south-central 
Idaho - Since 1955 Taylor has been making 
a detailed survey of the living mollusks 
of south-central Idaho in conjunction with 
geologic studies. The sparse records of 
the two species of Hinkleyia in this area 
are therefore not due to inadequate 
collecting. 

The Snake River valley in the area 
between Twin Falls and Glenns Ferry is 
a nearly flat or gently rolling arid plain 
cut by the canyon of the Snake River. It 
is naturally vegetated by little more than 
sagebrush and grass. Habitats suitable 
for aquatic mollusks are restricted to the 
Snake River, its few perennial tributaries, 
and irrigation ditches and artificial reser- 
voirs. Stagnicola caperata occurs only in 
the lowlands close to the Snake River. At 
all known localities it is in situations 
created or influenced by irrigation water. 

Volcanic hills of basalt and latite rise 
above the irrigated plains both north and 
south of the Snake River. These are the 
Mount Bennett Hills north of the river, 
and the Rock Creek Hills in southeastern 
Twin Falls County. They are only slightly 
less arid than the lowland, and have aspen 
trees or conifers only on north slopes or 
in protected places. In both of these 
upland areas the habitat of S. montanensis 
is similar- small, seasonal streams or 
seepages. These are the farthest up- 
stream locations of perennial or nearly 
perennial water. During the spring run- 
off these streams are about 2 to 4 feet 
wide and several inches deep, but in 



summer they dwindle to only a trickle, or 
a series of scarcely connected shallow 
pools, and may dry up entirely in the 
uppermost parts of their courses. S. 
montanensis was common in the pools 
in these small water courses, staying in 
the deeper water rather than crawling 
about on mud barely in or out of the water, 
as Fossaria dalli or F. obrussa usually 
do. At most places where S. montan- 
ensis was found alive it was the only 
aquatic moUusk; rarely Pisidium casert- 
anum was associated. 

One locality (PI. Ш, Fig. 1) deserves 
special mention because it is the place 
from which the dissected series comes, 
and at which the snails were found 
aestivating. The stream is a small, 
seasonal rivulet tributary to the South 
Fork of Shoshone Creek. It runs through 
a grove of aspen and pine trees; beside 
the stream are sparse willows. The 
bottom is formed of platy cobbles of latite, 
the local bedrock, with mud and some 
gravel in the hollows. On September 1, 
1955, the stream had shrunk to a few 
pools (16 C.) in which 5. montanensis 
was common. On September 2, 1957, 
when the photograph was taken, no water 
remained in the stream bed. The snails 
were found adhering to the under sides of 
stones and logs in the low spots of the 
bottom. They revived promptly when 
placed in water, and were preserved for 
dissection. The only unusual feature 
of the shells from this locality is their 
corrosion (see PI. I, Fig. 3). 

Description of habitats in east-central 
Idaho - In the Teton River drainage in 
east-central Idaho, Stagnicola montan- 
ensis is the only known species of 
Hinkleyia. The two localities where Taylor 
has collected it are roadside ditches. 
These situations were apparently more 
like those where S. caperata is found 
elsewhere than like other habitats of S. 
montanensis . 

In sec. 35, T. 6N., R. 45 E., roadside 
ditches on either side of Idaho state high- 
way 33 just north of the bridge over the 
South Fork of Leigh Creek were dry at the 
time of collection. The lower spots were 



SUBGENUS HINKLEYIA (LYMNAEIDAE: STAGNICOLA) 



269 



PLATE Ш 
Habitats of Stagnicola montanensis 







1 



FIG. 1. RcLbitât oí Stagnicola montanensis 
at the type locality in the headwaters of 
the South Fork of Shoshone Creek, Twin 
Falls Co., Idaho. View eastward, upstream 
showing the seasonally dry stream bed. 
On Sept. 1, 1955, the stream had shrunk 
to a few pools in which S. montanensis v^a.s 
common. On Sept. 2, 1957, no water 
remained. S. montanensis was found 
adhering to the undersides of stones and 
logs in the low spots of the bottom. No 
other freshwater moUusks were found. 
Photograph by D. W. Taylor, Sept. 2, 1957. 







FIG. 2. Rabitâtoî Stagnicola montanensis 
in the canyon of Cottonwood Creek, 
Franklin Co., Idaho. View westward, up- 
stream, in the upper area of seepage of 
a spring on the south side of the canyon. 
The smallest pools at the head of the 
seepage were inhabited by 5. montanensis, 
Fossaria dalli (Baker), F. obrussa (Say), 
Gyraulus circumstriatus (Tryon), Pisi- 
dium casertanum (Poli) and a small hydro - 
biid. Larger pools (foreground) had S. 
montanensis, S. eZodes (Say), Physagyrina 
(Say), Pisidium casertanum. (Poli) and the 
hydrobiid. Photograph by D. W. Taylor, 
Sept. 14, 1959. 



270 



TAYLOR, WALTER AND BURCH 



damp, but tall grasses grew all through 
the ditches and there was no trace of 
submergent aquatic plants. A few juvenile 
S. montanensis were living, but numerous 
adult shells were empty. The only associ- 
ated mollusks were the land snails Discus 
cronkhitei (Newcomb), Nesovitrea elec- 
trina (Gould), and empty shells of an 
indeterminate succineid. 

Six miles south of this locality, on the 
south side of Driggs, Stagnicola montan- 
ensis was found again in a roadside ditch 
on the west side of state highway 33. The 
ditch drained northward into a minor 
stream which was shown to be perennial by 
patches of submergent aquatic vegetation 
and by the continued moderate flow even in 
late summer. The ditch was mostly dry, 
but close to the stream the hollows were 
wet and at the end of the ditch there was a 
large pool 3 to 4 feet wide and 12 to 18 
inches deep (PI. IV, Fig. 1). S. montan- 
ensis was in slowly flowing water at the 
culvert, in quiet water in the pool, and in 
the dried-up hollows of the drainage ditch. 
Associated то\\\1Бк.в^ ere Stagnicola {s.s.) 
elodes, (Say), Gyraulus circumstriatus 
(Tryon), and Aplexa hypnorum (Linnaeus). 
These snails are often found with S. ca/)er- 
ata in the eastern United States, and they 
reinforce the impression gained from the 
habitat that here S. montanensis is in a 
place where S. caperata might be expected 
instead. 

Description of habitats in southeastern 
Idaho - In Franklin County, Idaho, D. W. 
Taylor and R.C. Bright found S. caperata 
and S. montanensis at one locality each. 
On thewestsideof the Bear River in north- 
ern Cache Valley, sec. 20, T.15S.,R. 39 E., 
S. caperata was common in a roadside 
ditch. The standing water was about 2 feet 
wide and up to 6 inches deep. The sparse 
vegetation gave the impression that the 
ditch had recently been scraped. S. caper- 
ata was the only moUusk. 

At the south end of Gentile Valley S. mon- 
tanensis was common in a spring on the 
south side of Cottonwood Creek. The spring 
issued from a number of small sources 
next to the steep south wall of the canyon, 
and from among cobbles and boulders in the 
canyon floor (PI, III, Fig. 2). At the upper 



area of seepage, hollows and crevices 
among the stones contained some water- 
cress. Increasedvolume produced a small 
rivulet which formed and kept fresh quiet 
pools a foot or 2 across, 3 to 4 inches deep, 
bordered by watercress, and with a soft 
mud bottom. Several such sources com- 
bined in a pool several feet across, about 6 
inches deep, stagnant, vjithChara, Myrio- 
phyllum, filamentous green algae, and 
watercress at the edge. This pool emptied 
by a small stream into Cottonwood Creek. 

The changes in volume and nature of the 
water bodies were found to be correlated 
with changes in the moUusk population. In 
the smallest water bodies at the spring 
sources S. m,ontanensis , Pisidium casert- 
anum (Poli), and a small hydrobiid were 
common. Gyraulus circumstriatus (Try- 
on), Fossaria dalli (Baker) and F.obrussa 
(Say) were also present but rare. The 
larger, fresh pools 1 to 2 feet in diameter 
yielded S. montanensis, Pisidium caser- 
tanum, and the hydrobiid as well as Sia^^m- 
cola (s.S.) elodes {Sa.y) a.nd Physa gyrina 
(Say). The last two species were the only 
mollusks in the stagnant pools and the 
lower parts of the discharge into cotton- 
wood Creek. The terrestrial snail 
Oxylomzi was found also among grasses and 
watercress in the seepage area and along 
the outflow of the large pool. 

Stagnicola montanensis occurred in 
pools varying in size from 1 or 2 feet to 
2 or 3 inches in diameter, in water without 
perceptible current but nevertheless kept 
fresh by seepage. It also was found in 
slow current, among algae in the rivulet 
toward the large pool. It was most abundant 
in very small pools in the seepage area, 
in watercress, on mud and leaves, always 
submerged. 

APPENDIX 
Fossil Localities 

Fossil localités in the following list 
are arranged stratigraphically from older 
to younger, and geographically from north 
to south and west to east. Locality numbers 
are those of the U. S. Geological Survey 
Cenozoic series. 



SUBGENUS Я/ЛГ/СЬЕ УМ (LYMNAEIDAE: STAGNICOLA) 271 

PLATE IV 
Habitats of Stagnicola montanensis 










FIG. 1. Habitat of Stagnicola montanensis at the south side of Driggs, Teton County, Idaho. A small 
perennial stream flows westward under the highway, emerging through the culvert opening in left center, 
and continues off left. The pool in the roadside ditch (foreground) was inhabitated by Stagmcola elodes 
(Say), Gyraulus circumstriatus (Tryon), and Aplexa hypnorum (Linnaeus) as well as S. montanensis. Photo- 
graph by D. W. Taylor, August 28, 1959. 

FIG. 2. Habitat of Stagnicola montanensis at Round Spring, Gooding Co., Idaho. View south down the bed 
of Hot Creek just below the source of the small spring. Elsewhere the stream bed is dry, but the spring 
provides water along a distance of about 150 feet. Small pools of water are visible among the sedges growing 
in a bed of mud and cobbles and pebbles of platy latite. S. montanensis was the only mollusk found. Photo- 
graph by D. W. Taylor, July 26, 1959. 



272 



TAYLOR, WALTER AND BURCH 



PLIOCENE 

19105. Teton Co., Wyoming. GrandTeton 
National Park sheet (1954) 1:62,500. 
SE 1/4 sec. 25, T. 42 N., R. 116 W. 
800 feet west, 800 feet north of south- 
east corner. Exposure along irrigation 
ditch by shack. Upper claystone and 
pumicite member of Teewinot For- 
mation of Love (1956b, p 90-91). D.W. 
Taylor, J. D. Love, 1955, 1956. 

MIDDLE PLEISTOCENE 

The following localitites are all in the 
Bruneau Formation, of middle Pleis- 
tocene age (Malde and Powers, 1962). 
Localities 19219, 19222, and 20410 are 
in a brown soil horizon developed in 
the top of the lake beds of this for- 
mation. 

19219. Twin Falls Co., Idaho. Hagerman 
quad. (1950) 1:24,000. SW 1/4 sec. 16, 
T. 7 S., R. 13E.250ftE., 500 ft N., and 
350 ft E. 700 ft N. of SW corner. 3180 ft 
elev. Brown soil. D. W. Taylor, 1955. 

19222. Twin Falls Co., Idaho. Hagerman 
quad. (1950) 1: 24,000. SW 1/4 sec. 17, 
T. 7 S., R. 13 E., 150 ft W., 1525 ft N. 
to 50 ft W., 1625 ft N. of SE corner. 
3180 ft elev. Brown soil. D.W.Taylor, 
1955. 

19225. Twin Falls Co., Idaho. Hagerman 
quad. (1950) 1: 24,000. Center of 
SW 1/4 sec. 16, T. 7 S., R. 13 E. 
2875 ft-2940 ft elev. Sand on both sides 
of main gulch draining sec. 17. D. W. 
Taylor, 1955. 

20105. Elmore Co., Idaho. Glenns Ferry 
quad. (1948) 1: 24,000. NW 1/4 sec. 15, 
T. 6 S., R. 10 E. 2300 ft E., 2050 ft S. 
of NW corner. 2800 ft elev. H. E. 
Malde, 1956. 

20107. Elmore Co., Idaho. Glenns Ferry 
quad. (1948) 1: 24,000. NE 1/4 sec. 22, 
T. 6 S., R. 10 E. 3150 ft E. 550 ft S. of 
NW corner. 2790 ft elev. Shells from 
light-gray to white-weathering clay 
about 10 ft below l/2in basaltic glass 
sand. D. W. Taylor, 1956. 

20109. Elmore Co., Idaho. Pasadena 
VaUey quad. (1948)1:24,000. NE 1/4 
sec. 22, T. 6 S., R. 10 E. 800 ft S., 
1400 ft - 1100 ft W. of NE corner. 



2785 ft -2800 ft elev. Scattered, scarce 
shells from light gray clay ft - 15 ft 
below l/2in basaltic glass sand at about 
2800 ft elev. D.W. Taylor, H. E. Malde, 
1956. 
20112. Elmore Co., Idaho. Pasadena 
VaUey quad. (1948) 1: 24,000. SE 1/4 
sec. 23, T. 6 S., R. 10 E. 600 ft W., 
350 ft N. of SE corner. 2800 ft elev. 
Clay below basaltic glass sand. H. E. 
Malde, 1956. 
20120. Elmore Co., Idaho. Pasadena 
Valley quad. (1948) 1: 24,000. NW 1/4 
sec. 21, T. 6 S., R. 11 E. 2200 ft E., 
1750 ft S. of NW corner. 2900 ft elev. 
Fossils from about 5 ft above base of 
gray sand exposed on steep, west- 
facing slopes on E. side of Deer Gulch, 
immediately north of tributary from 
east. D. W. Taylor, 1956. 
20404. Owyhee Co., Idaho. Oreana quad. 
(1950) 1: 24,000. SE 1/4 sec. 14, T. 
4 S., R. 1 W. 1425 ft N., 550 ft W. of 
SE corner. 3025 ft elev. N. R. 
Anderson, 1956. 
20410. Twin Falls Co., Idaho. Hagerman 
quad. (1950) 1: 24,000. NE 1/4 sec. 
17 and NW 1/4 sec. 16, T. 7 S., R. 13 
E. 175 ft W., 1750 ft S. of NE corner 
to 350 ft E., 1950 ft S. of NW corner. 
3180 ft elev. Brown soil. D.W. Taylor, 
1955. 
20472. Owyhee Co., Idaho. Castle Butte 
quad. (1948) 1: 24,000. SW 1/4 sec. 
18, T. 4 S., R 2 E. 2350 ft E., 1500 ft 
N. of SW corner. 2530 ft elev. Sedi- 
ments below basaltic glass sand. N. 
R. Anderson, 1957. 
In the American Falls Reservoir area, 
southeastern Idaho, the oldest Pleistocene 
formation is the Raft Formation. It is of 
middle Pleistocene age, overlain by the 
American Falls Lake beds whose base is 
probably of Illinoian age (Love and Taylor, 
1962). Quite possibly the Raft Formation 
is equivalent to part of the Bruneau For- 
mation. 

20478. Power Co., Idaho. N^1/4SW 1/4 
sec. 22, T. 9 S., R. 28 E. Base of bluff 
at Snake River, in Wildlife Refuge about 
8 miles W. of Massacre Rocks on U. 



SVBGENVS HINKLEYIA (LYMNAEIDAE: STAGNICOLA) 



273 



S. highway 30 N. Raft Formation. W. 
J. Carr and D. E. Trimble, 1957. 
LATE PLEISTOCENE 

In the Glenns Ferry-Hagerman area, 
southwestern Idaho, a few fossils have 
been found in late alluvium. Locality 
20413 is in a young alluvial unit not 
formally named (H. E. Malde, written 
communication, 1961). 
20413. Twin Falls Co., Idaho. Hagerman 
quad. (1950) 1: 24,000. SW 1/4 sec. 16, 
T. 7 S., R. 13E. 1650ft E., 975 ft N. of 
SW corner. 2900 ft elev. Limey light 
gray to white fine sand and silt. D. W. 
Taylor, 1955. 
The following localities are in late 
Pleistocene sediments in the vicinity of 
the American Falls Reservoir, south- 
eastern Idaho. Overlying the Raft For- 
mation is a fluviatile gravel at the base of 
the American Falls Lake beds. The gravel 
is probably of Illinoian age (Love and 
Taylor, 1962). The upper part of the lake 
beds is no younger than early Wisconsin. 
The alluvial units are younger : the Michaud 
Gravel is early Wisconsin, deposited by 
overflow of Lake Bonneville, and the 
other sediments are of still later Wis- 
consin age. 

19169. Power Co., Idaho. Michaud quad. 
(1937) 1: 62,500. SE 1/4 sec. 3, T. 6 
S., R. 32 E. Shore of American Falls 
Reservoir. Basal gravel of American 
Falls Lake beds. M. L.Hopkins, 1954. 
20474. Power Co., Idaho. American Falls 
quad. (1936) 1: 62,500. SE1/4NW 1/4 
sec. 29, T. 7 S., R. 31 E. 4350 ft elev. 
Gravel pit exposures of older alluvium 
as mapped by W. J. Carr and D. E. 
Trimble (written communication, 1961). 
D. W. Taylor and others, 1957. 
20477. Power Co., Idaho. Rockland quad. 
(1937) 1: 62,500. SE 1/4 sec. 14, T. 9 
S., R. 30 E. 550 ft W., 200 ft N. of SE 
corner. Rock Creek road. W. J. Carr 
and D. E. Trimble, 1957. 
20479. Bingham Co., Idaho. American 
Falls quad. (1936) 1: 62,500. NW 1/4 
sec. 22, T. 5 S., R. 31 E. Two miles 
north of Aberdeen. W. J. Carr and 
D. E. Trimble, 1957. 
21057. Power Co., Idaho. Michaud quad. 



(1937) 1: 62,500. S 1/2 NE 1/4 sec.3, 
T. 6 S., R. 32 E. Exposure in cliff at 
edge of American Falls Reservoir. 
Sand and gravel in lower part of A- 
merican Falls Lake beds; or Michaud 
gravel. M. L. Hopkins and others, 1957. 

21636. Power Co., Idaho. American Falls 
quad. (1936) 1: 62,500. NE1/4NW 1/4 
sec. 32, T. 7 S., R. 31 E. Exposure in 
ditch for Michaud Flats pipeline. Older 
alluvium or Aberdeen terrace deposits. 
W. J. Carr, 1957. 

21643. Power Co., Idaho. American Falls 
quad. (1936) 1: 62,500. NE 1/4 SW 1/4 
sec. 30, T. 7 S., R. 31 E. Bluff at edge 
of reservoir. Ten feet below base of 
persistent white blocky clay. American 
FaUs Lake beds. W. J. Carr, 1958. 

22332. Power Co., Idaho. Michaud quad. 
(1937) 1: 62,500. NW 1/4 NE 1/4 sec. 

I, T. 7 S., R. 32 E. 4445 ft elev. Road- 
cut exposure. Possibly Sunbeam For- 
mation. W. J. Carr, 1960. 

The following localities are in an un- 
named alluvial unit in Marsh Creek valley. 
This unit appears from reconnaissance by 
R. C. Bright and D. W. Taylor to be older 
than the overflow of Lake Bonneville, hence 
probably pre-Wisconsin. 
22328. Bannock Co., Idaho. Pocatello 
sheet (1958) 1: 250,000. North side 
NE 1/4 sec. 31, T. 11 S., R. 37 E. 
Road cut exposure on south side of 
Woodland road 2.6 miles west of 
Downey. R. С Bright, D. W. Taylor, 
1959. 
22410. Bannock Co., Idaho. Pocatello 
sheet (1958) 1: 250,000. SE 1/4 sec. 

II, T. 10 S., R. 36 E. Robin road west 
of Arimo. Big cut west of top of 
pediment and about 300 yards west of 
big gravel pit. On east flank of first 
big gully west of top of pediment. South 
side of road in middle of cut. R. C. 
Bright, 1959. 

The follwing localities are in sediments 
deposited in an early Wisconsin lake named 
Lake Thatcher by Bright (1960). Radio- 
carbon dates (W-704, W -855) of 32, 500 and 
27,500 years were obtained from samples 
of fossil shells from these deposits (Rubin 
and Alexander, 1960). 



274 



TAYLOR, WALTER AND BURCH 



21143. Franklin Co., Idaho. Prestonquad. 
(1918) 1: 125,000. NE 1/4 sec. 1, T. 
12 S., R. 40 E. Cut on west side of 
Idaho state highway 34. Lake Thatcher 
deposits. R. С Bright, 1957. 

22396. Caribou Co., Idaho. Bancroft quad. 
(1949) 1: 625,000. NE 1/4 SW 1/4 sec. 
29, T. 10 S., R. 40 E. Cut on west side 
of road below telephone pole and guy. 
Sandy unit at base of cut, just a few 
feet above ditch. R. C. Bright, 1958. 

23025. Caribou Co., Idaho. Prestonquad. 
(1913) 1: 125,000. NE 1/4 NE 1/4 
SW 1/4 sec. 9, T. 11 S., R. 41 E. Road 
cut at sharp turn in road at base of 
grade. Elev. about 5300 feet. Lake 
Thatcher deposits. R. С Bright, 1961. 

23027. Caribou Co., Idaho. Bancroftquad. 
(1949) 1: 625,000. NE 1/4 NE 1/4 sec. 
31, T. 10 S., R. 40 E. Just below 
gravel-capped knob about 1/2 mile west 
of Harris ranch house. Elev. about 
5340 feet. Lake Thatcher deposits. 
R. С Bright, 1961. 

23033. Caribou Co., Idaho. Prestonquad. 
(1918) 1: 125,000. Center SW 1/4 SE 
1/4 sec. 26, T. 11 S., R. 40 E. Wawn 
Hogan water well, depth 123-128 feet. 
Lake Thatcher deposits? R. C. Bright, 
1961. 

23037. Caribou Co., Idaho. Prestonquad. 
(1918) 1: 125,000. Center N 1/2 sec. 
12, T. 11 S., R. 40 E. About 1/4 mile 
south of elev. 5376 on Idaho state high- 
way 34, in road cut on west side of road. 
Elev. about 5345 feet. Lake Thatcher 
deposits. R. С Bright, 1961. 

23061. Caribou Co., Idaho. Prestonquad. 
(1918) 1: 125,000. SW 1/4 SW 1/4 
SW 1/4 sec. 8, T. 11 S., R. 41 E. Road 
cut at north side of road. About 1/5 
mile west of Bitten' s ranch on divide 
separating East Fork Whisky Creek 
from West Fork Trout Creek. Elev. 
about 5270 feet. Lake Thatcher 
deposits. R. C. Bright, 1961. 

23066. Caribou Co., Idaho. Prestonquad. 
(1918) 1: 125,000. NW 1/4 SW 1/4 
SE 1/4 sec. 24, T. US., R. 40 E. About 
300 yards west of basalt cliff in sand 
pit on side of prominent knob. Some 
probable Lake Thatcher material re- 



worked in shore deposit of Lake Bonne- 
ville. Elev. about 5100 feet. R. C. 
Bright, 1961. 
The following localities are from sedi- 
ments which may be related to a former 
high stand of Bear Lake, Idaho -Utah. 
21062. Bear Lake Co., Idaho. Montpelier 
quad. (1909) 1: 125,000. NW 1/4 sec. 
30, T. 12 S., R. 44 E. Fossiliferous 
sand from west side of pit. F. C. 
Armstrong, 1949. 
22429. Bear Lake Co., Idaho. Montpelier 
quad. (1909) 1: 125,000. T. 11 S., R. 
43 E. Two miles south of Nounan in 
road cut on west side of Road. R. C. 
Bright, 1960. 
The following localities are in deposits 
of Lake Bonneville, Idaho-Utah. Locality 
22359 is of rather recent age; those from 
the Saltair core range through much of the 
late Pleistocene according to the inter- 
pretations by Eardley and Gvosdetsky 
(1960). 

21112. Salt Lake Co., Utah, Core from 
Saltair, depth 271 ft 4in - 271 ft 6in. 
A. J. Eardley, 1958. 
21120. Salt Lake Co., Utah. Core from 
Saltair, depth 428 ft 7in - 428 ft lOin. 
A. J. Eardley, 1958. 
21122. Salt Lake Co.. Utah. Core from 
Saltair, depth 435 ft Hin - 436 ft lin. 
A. J. Eardley, 1958 
21124. Salt Lake Co., Utah. Core from 
Saltair, depth 463 ft 10 l/2in - 464 ft 
l/2in. A. J. Eardley, 1958. 
22359. Box Elder Co., Utah. SW 1/4 sec. 
34, T. 9 N., R. 3 W. Depth 12in - 24in, 
along Bear River. Post-Provo. J. H. 
Feth, 1953. 
22395. Franklin Co., Idaho. Prestonquad. 
(1918) 1: 125,000. NE 1/4 NW 1/4 
NE 1/4 sec. 28, T. 15 S., R. 39 E. About 
1.3 miles duewestof center of Preston. 
In road cut just south of highway 89 at 
intersection of road to Refuge Club. 
Prominently cross-bedded sand. Provo 
sediments. 4702 ft ± elev. R. С Bright, 
1958. Shells from this locality were 
dated at 13,900 -400 radiocarbonyears 
by the U. S. Geological Survey labo- 
ratory (sample W-899). 
23069. Caribou Co., Idaho. Prestonquad. 



SUBGENUS HINKLEYIA (LYMNAEIDAE: STAGNICOLA) 



275 



(1918) 1: 125,000. SW 1/4 SW 1/4 
NE 1/4 sec. 24, T. lis., R. 40 E. About 
50 yards north of Jay Turner's house 
in tan sands. Elev. about 5100 feet. 
R. C. Bright, 1961. 
The following locality is presumably of 

late Pleistocene age: 

19192. Humboldt Co., Nevada. Antler Peak 
quad. (1940) 1: 625,000. Sec. 18, T. 
33 N., R. 43 E. 5050' elev. at range 
front. Trout Creek valley at Marigold 
Mine. Shells from red-brown clay from 
drill hole in valley floor. R. J. 
Roberts. 

ACKNOWLEDGMENTS 

For permission to study specimens 
under their charge we are grateful to R. 
T. Abbott, Academy of Natural Sciences, 
Philadelphia; G. D. Hanna and A. G.Smith, 
California Academy of Sciences; H. A. 
Rehder, U. S. National Museum, and H. 
G. Rodeck, University of Colorado 
Museum. We wish to acknowledge also 
the aid of Linda L. Bush, Department of 
Biology, Western Michigan University for 
preparing many of the cytological slides, 
and to R. С Bright, Department of 
Geology, University of Minnesota, for 
advice on the statistical analysis. 
Drawings of shells are by Mrs. Elinor 
Stromberg, U. S. Geological Survey, except 
for text Figure 1 which is by Miss Roberta 
Wigder, U. S. Geological Survey. 

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traeger). xii + 834 p. 



^^Obtainable in microfilm form from Univ. Microfilms, Ann Arbor, Michigan, U.S.A. 



SUBGENUS Я/]^/(:Ь£ГМ (ЬУМКАЕШАЕ: STAGNICOLA) 277 

ZUSAMMENFASSUNG 

SÜSSWASSERSCHNECKEN DER UNTERGATTUNG HINKLEYIA (LYMNAEmAE: 
STAGNICOLA) AUS DEN WESTLICHEN VEREINIGTEN STAATEN 

Die Untergattung Hinkleyia, die bisher nur aus einer einzigen Art, Stngnicola caperata 
(Say) bestand, wird hier um 2 Arten erweitert. Und zwar fügen wir auf Grund gewisser 
konchyliologischer sowie anatomischer Merkmale S. montanensis (Baker) hinzu und, 
auf Grund konchyliologischer Merkmale allein, S./)¿Zsbr>'¿ (Hemphill). Neue Erkenntnisse 
gestatten nun eine revidierte Diagnose von Hinkleyia, welcher, obwohl sie einige kenn- 
zeichnende Eigenheiten aufweist, doch nur subgenerischer Rang zusteht. 

Sechzehn Exemplare einer konservierten Serie von S. montanensis wurden seziert. 
Anatomisch waren sie S. caperata so ähnlich, dass keinerlei Unterscheidungsmerkmale 
mit Sicherheit erkannt werden konnten. 

Die beiden Arten kann man an ihren Schalen erkennen. S. montanensis hat gewöhnlich 
eine schmälere und mehr langgestreckte Form als S. caperata, die eher geschwollen 
ist, aber diese Kennzeichen überschneiden sich, so dass die einzigen immer verläss- 
lichen Charaktere in der Oberfläche und Skulptur der Schale zu finden sind. Verhält- 
nismässig auffällige spiralig verlaufende Periostrakumleistchen kennzeichnen S. caper- 
ata, während eine glänzende, mit feinstem, spiral angeordnetem Sichelmuster verse- 
hene Oberfläche, ohne Leistchen, für S. montanensis charakteristisch ist. 

Die anatomischen Merkmale, die diese beiden Arten mit typischen amerikanischen 
Stagnicola gemein haben und die, soweit bekannt, ausschliesslich bei diesen vorkommen, 
sind: ein gut entwickelter vaginaler Sphinktermuskel; ein grosses Divertikulum am 
proximalen Ende der oberen Prostata; eine verhältnismässig dicke und durze Pe- 
nisscheide; ein relativ kurzer bilateral symmetrischer Penis mit einem muskulären 
"Knoten" in seiner ungefähren Mitte; und eine gut entwickelte Serie von deutlich 2- 
zackigen Seitenzähnen an der Radula, 

Hinkleyia (d.h. S. montanensis und S. caperata) unterscheidet sich von typischen 
Stagnicola durch einen etwas verschieden und weniger stark entwickelten vaginalen 
Sphinkter, einen bemerkenswert dicken Vas deferens und einen kürzeren Penis, der 
einen weniger prominenten, mehr distal gelegene "Knoten" hat. Bemerkenswert ist 
ferner die sich verjüngende, distal vom Knoten gelegene Partie des Penis, die kurz und 
dick ist und sich vom starken proximalen Teil viel weniger klar absetzt als dies bei 
Stagnicola s.S. der Fall ist. Beide Arten haben auch eine ungewöhnlich kurze und starke 
Penisscheide, eine Prostata von besonderem Bau und einen in seinem unteren Teil 
ungewöhnlich robust entwickelten Spermathekdukt. Asserdem zeigen sie in der Be- 
schaffenheit und Pigmentierung ihrer gesamten Anatomie Ähnlichkeiten, welche dazu 
beitragen sie weiterhin von anderen genügend bekannten Lymnaeiden abzusondern. Auch 
sind ihre Körper stark pigmentiert und, im lebenden Zustand, Fuss und Tentakeln 
recht schlank. 

Es wurde ferner festgestellt, dass S. montanensis bei einer Schalenlänge von 6-7 mm 
geschlechtsreif wurde. Es wird angenommen, dass der noch unbekannte Laich dieser 
Art dem eigenartigen von S. caperata gleichen dürfte, der sich durch die relative Dicke 
der individuellen EihüUen und der unscheinbaren dünnen äusseren Tunika der Laichmasse 
auszeichnet. 

Weiters wurde ermittelt, dass eine Art, die als Untergattung Nasonia unter Stagnicola 
eingereiht worden war, nahe mit Fossar¿a verwandt ist und daher nicht mit Ягп/г^еуга. 
Die Möglichkeit einer näheren Beziehung zwischen S. arciz'ca und Ягп^г;е>>га statt Sia^g^- 
nicola s.S. wurde in Betracht gezogen aber auf Grund von neuerem anatomischen 
Beweismaterial abgelehnt. 

Die haploiden Chromosomenzahlen von S. montanensis und S. caperata betragen 18; 
die nachgewiesene diploide Chromosomenzahl von S. montanensis ist 36. Diese Zahlen 
sind für Basommatophoren im allgemeinen kennzeichnend. In den Einzelheiten der 
Gametogenese, einschliesslich der monozentrischen Natur der Chromosome scheint 
Hinkleyia den anderen Lymnaeiden zu gleichen. Normalerweise verläuft die Spermato- 
genese in 6 spermatogonischen Teilungen, auf welche 2 meiotische folgen. Es kommen 
daher die spermatogonischen Zellen in Büscheln zu 2, 4, 8, 16 und 32 vor, die primären 
Spermatozyten in Büscheln zu 64, die sekundären in solchen zu 128 und die Spermatiden 
sowie der Sperm in Büscheln zu 256. 

Von besonderem zytologischen Interesse in der Gametogenese von S. caperata und 
S. montanensis ist die Anwesenheit von 5-7 grossen Chromatinkörpern in jedem Zellkern 
während der frühen Prophase der ersten meiotischen Teilung der Spermatogenese, wie 



278 TAYLOR, WALTER AND BURCH 

sie für lymnaeide Schnecken noch nie beobachtet wurde. Diese Chromatinkörper stellen 
vielleicht ein weiteres Kennzeichen für die nahe Verwandtschaft dieser beiden Arten 
dar. 

In den westlichen Vereinigten Staaten hat S. montanensis eine weite Verbreitxing im 
östlichen Teil des Entwässerungsgebietes des Columbiailusses und dem nördlichen 
des "Great Basin", einem Gebiet, das sich von Westmontana und Utah bis ins süd- 
liche Idalio und Mittelnevada erstreckt. Man findet die Art in für Lymnaeiden ganz 
ungewöhnlichen Wohnplätzen, nämlich in Quellen und klaren Bergbächen. Das grössere, 
beinahe das gesamte nördliche Nordamerika umfassende Verbreitungsgebiet von S. 
caperata schliesst dasjenige von S. montanensis ein. Man findet S. caperata in Bewäs- 
serungsgräben und schlammigen, unbeständigen Gewässern in denen S. montanensis 
nicht lebt. Durch Beschreibungen spezifischer Standorte und durch Landkarten welche 
die geographische Verbreitung (lebend und fossil) anzeigen, werden Anhaltspunkte 
für nicht morphologische Unterschiede zwischen den beiden Arten gegeben. Die be- 
obachtete geographische Trennung der Arten ist teilweise auf ihre verschiedenartigen 
ökologischen Bedürfnisse zurückzuführen, wahrscheinlich aber auch zum Teil auf die 
geologische Vorgeschichte des Gebietes. S. pilsbryi istnur durch die Originalsammlung 
und aus einem einzigen Fundort im westlichen Utah bekannt; ökologische Angaben fehlen. 



RESUME 

MOLLUSQUES FLUVIÁTILES DU SOUS-GENRE HINKLEYIA 
(LYMNAEIDAE: STAGNICOLA) DES ETATS UNIS OCCIDENTAUX 

Le sous-genre Hinkleyia, ne comprenant jusqu'à présent que l'espèce Stagnicola 
caperata (Say), est augmenté ici de deux espèces: S. montanensis (Baker) et S. pilsbrvi 
(Hemphill), la première d'après de critères conchyliologiques et anatomiques, et la 
seconde uniquement d'après des caractères conchyliologiques. Ces nouvelles données 
entraînent une révision de la diagnose de Hinkleyia qui, quoique possédant plusieurs 
traits particuliers, ne mérite pourtant qu'un rang subgénérique. 

Seize spécimens d'une série de S. montanensis provenant de l'Idaho furent disséqués. 
Anatomiquement ils ressemblaient de si près à S. caperata, qu'aucun caractère dis- 
tinctif ne put être trouvé. 

Les 2 espèces se distinguent par leur coquille. Celle de S. montanensis est d'habitude 
plus étroitement allongée que celle de S. caperata, plus gonflée; mais ces caractères 
sont variables et les seuls critères sûrs et constants se trouvent dans la sculpture de 
la surface. Des crêtes périostracales spirales relativement proéminentes déterminent 
la diagnose de S. caperata tandis qu'une surface luisante, dépourvue de telles crêtes, 
mais garnie de séries spirales de minuscules croissants, détermine celle de S. mon- 
tanensis. 

Les caractères anatomiques, particuliers, communs aux stagnicoles typiques améri- 
caines et à ces 2 espèces sont: un sphincter vaginal bien développé; un grand diverticule 
attenant au bout proximal de la prostate supérieure; une gaine péniale relativement 
épaisse et courte; un pénis relativement court à Symmetrie bilatérale, ayant un "noeud" 
musculaire à peu près à mi-longueur, et une série bien développée de dents radulaires 
latérales clairement bicuspidées. 

Comparés aux Stagnicola typiques, les Hinkleyia (tout-au moins S. montanensis et 
S. caperata) montrent un développement un peu différent et moins proéminent du 
sphincter vaginal; un vas deferens remarquable par son épaisseur et un pénis plus 
court, ayant un "noeud" moins proéminent et de position plus distale. Notons aussi que 
la portion effilée du pénis, distale par rapport au noeud, est courte, forte et moins 
individualisée par rapport à la portion proximale que chez les Stagnicola proprement 
dits. Les 2 espèces possèdent aussi une gaine péniale remarquablement courte et 
forte, une prostate de structure particulière et un conduit spermatique plus robuste 
que d'ordinaire dans sa partie inférieure. Dans leur pigmentation et leur anatomie 
générale elles montrent des similitudes additionelles servant aussi à les séparer des 
autres Lymnaeidés suffisamment connus. Leurs corps sont fortement pigmentés. A 
l'état vivant, les pieds et tentacules sont relativement sveltes. 

A une taille de 6 à 7 mm les S. montanensis avaient atteint la maturité sexuelle. 
Nous supposons que la ponte encore inconnue de cette espèce ressemblera de près 
à celle de S. caperata qui est très à-partau fait de l'épaisseur relative des enveloppes 



SUBGENUS HINKLEYIA (LYMNAEffiAE: STAGNICOLA) 279 

de chaque oeuf et du fait de la minceur de la tunique extérieure de la masse. 

L'examen anatomique a aussi montré qu'une espèce rangée dans le sous-genre 
Nasonia du genre Stagnicola est étroitement apparentée à Fossaria et, par conséquent, 
pas à Hinkleyia. La possibilité d'une affinité de S. árctica avec Hinkleyia plutôt 
qu'avec le sous-genre Stagnicola a été examinee, mais rejetée à la suite de nouvelles 
recherches anatomiques. 

Le nombre haploïde de chromosomes de S. montanensis et de S. caperata est de 18, 
Le nombre diploïde de S. montanensis est de 36. Ces nombres sont caractéristiques 
pour les mollusques basommatophores en général. Les détails de la gamétogénèse, y 
compris la nature monocentrique des chromosomes, ne semblent pas différer de ceux 
vus chez les autres lymnaeidés. Pendant la Spermatogenese il y a, normalement, 6 
divisions spermatogoniales, suivies de 2 divisions meiotiques. Les cellules sperma- 
togoniales se trouvent donc en bouquets de 2, 4, 8, 16 et 32; les spermatocytes primaires 
en bouquets de 64; les spermatocytes secondaires en bouquets de 128 et les sperma- 
tides et spermatozoïdes en bouquets de 256. 

Fait intéressant spécial dans la gamétogénèse de S. montanensis et de S. caperata: 
il y a 5 à 7 grands corps chromatiniens dans chaque noyeau cellulaire pendant les 
premiers stades de la prophase de la première division meiotique de la Spermatogenese; 
de pareils corps de chromatine n'ont été signalés chez aucun autre Lymnaeidé. Ils 
constituent peut-être un autre trait d'affinité de ces 2 espèces. 

S. montanensis est largement réparti dans l'ouest des Etats Unis d'Amérique, dans 
le bassin hydrographique oriental du fleuve Columbia et le versant nord du "Great 
Basin", un territoire allant du Montana occidental et de l'Utah jusqu'à l'Idaho méridional 
et le centre du Nevada. L'espèce habite sources et ruisseaux de montagne clairs, 
habitat inusité pour un lymnéide. L'aire de répartition de S. caperata, plus vaste, 
couvre la majeure partie de l'Amérique du Nord septentrionale, incluant celle de S. 
montanensis. S. caperata peuple des habitats tels que fossés d'irrigation et eaux 
boueuses saisonnières où S. montanensis ne se trouve pas. Ces différences d'habitat, 
et des cartes géographiques montrant leurs distributions actuelles et passées con- 
firment la distinction des deux espèces que nous avait enseignée la morphologie. La 
séparation géographique observée entre ces 2 espèces est partiellement liée à leurs 
besoins écologiques différents, mais probablement aussi, en partie, à l'histoire gé- 
ologique du territoire. S. pilsbryi n'est connu que par le matériel original, et d'une 
seule localité dans l'Utah occidental, sans aucune donnée écologique. 

RESUMEN 

CARACOLES FLUVL\LES DEL SUBGÉNERO HINKLEYIA (LYMNAEmAE: 
STAGNICOLA), DEL OESTE DE ESTADOS UNmOS 

El subgénero Hinkleyia, formado por una sola especie, Stagnicola caperata (Say), se 
amplía ahora por la adición de S. montanensis (Baker), en base a criterios anatómicos 
y conquiliológicos en la primera, y exclusivamente conquiliológicos en la segunda. Los 
nuevos datos obtenidos en este estudio permiten revisar la diagnosis de Hinkleyia, que 
posee varias características distintivas pero insuficientes para conferirle categoría 
genérica. 

La disección de 16 ejemplares preservados de 5. montanensis de Idaho reveló 
tal similitud con S. caperata que no ha sido posible distinguirlas anatómicamente. 

Las dos especies pueden distinguirse por la concha. En general, S. montanensis es 
más estrecha y alargada, y S. caperata más ancha, pero, como estes caracteres se 
sobreponen, sólo quedan como caracteres diagnósticos seguros la textura y la escultura 
superficiales. Así, S. caperata se caracteriza por costillas espirales del periostraco 
relativamente conspicuas y S. montanensis por una superficie lustrosa sin esa escultura, 
pero con series de minúsculos crecientes ordenadas en espiral. 

Los caracteres anatómicos comunes a estas dos especies y a las típicas Stagnicola 
americanas y, por lo que sabemos, exclusivos de ellas, son: esfínter vaginal bien 
desarrollado; grande divertículo anexo a la extremidad proximal de la parte superior 
de la próstata; vaina penial comparativamente corta y más bien robusta; pene corto, 
bilateralmente simétrico y con un "nudo" muscular en la parte media; y una serie 
bien desarrollada de dientes radulares laterales distintamente bicúspides. 

En comparación con las Stagnicola típicas, Hinkleyia (es decir, S. montanensis y S. 
caperata) tiene el esfínter vaginal menos desarrollado, el vas deferens notablemente 



280 SVBGEliUS HINKLEYIA (ЬУМКАЕШАЕ: STAGNICOLA) 

robusto у el pene más corto con un "nudo" menos prominente situado algún tanto más 
distalmente. Especialmente notable es la porción atenuada del pene, distal al "nudo", 
que es corta y robusta y mucho menos distintamente demarcada de la porción proximal 
gruesa que en las Stagnicola típicas. Además, ambas especies se caracterizan por la 
vaina penial más corta y gruesa que lo común, la conformación particular de la 
próstata y la notable robustez de la parte inferior del ducto de la espermateca. Otros 
caracteres que sirven para separarlas de otras especies de limneidos bien conocidas 
son la fuerte pigmentación del cuerpo y la delgadez relativa del pie y de los tentáculos 
en el animal vivo. 

Se descubrió también que S. montanensis llega a la madurez sexual al alcanzar su 
concha la longitud de 6 o 7 mm. Puede conjeturarse que la masa ovígera, desconocida 
en esta especie, demuestre ser similar a la de S. caperata, la cual se singulariza por 
el relativo espesor de la envoltura de los huevos individuales y por la delgada e incon- 
spicua túnica externa de la masa ovígera. 

La evidencia anatómica indica que una especie con anterioridad asignada a Stagnicola 
bajo el subgénero Nasonia se relaciona estrechamente con Fossaria y por lo tanto no 
es aliada a S. montanensis y S. caperata. Una posible afinidad especial de S. árctica 
con Hinkleyia, 'más bien que con el subgénero Stagnicola, fué considerada pero rechazada 
en base a los nuevos datos anatómicos. 

El número haploide de cromosomas de S. montanensis y S. caperata es 18; el 
número diploide de S. montanensis es 36. Estos números son característicos de los 
basomatóforos en general. Los detalles de la gametogénesis, incluyendo la naturaleza 
monocéntrica de los cromosomas, parecen ser los mismos que en otros limneidos. 
Durante la espermatogénesis ocurren normalmente 6 divisiones espermatogónicas, 
seguidas por 2 meióticas. Por lo tanto, los elementos germinales aparecen en racimos 
de 2, 4, 8, 16 y 32 para las espermatogonias, 64 para los espermatocitos primarios, 
128 para los espermatocitos secundarios, y 256 para las espermátidas y los esperma- 
tozoides. 

De especial interés citológico en la gametogénesis de S. montanensis y S. caperata, 
de lo que aun no se tenia noticia en otros limneidos, es la ocurrencia de 5 a 7 grandes 
cuerpos de cromatina en cada núcleo en el principio de la profase de la primera división 
meiótica de la espermatogénesis. Estos cuerpos cromáticos son quizá otro carácter 
demostrativo de una estrecha relación entre las dos especies. 

S. montanensis tiene amplia distribución en el oeste de Estados Unidos, en la región 
oriental del Río Columbia y septentrional de la Gran Cuenca, desde el oeste de Montana 
y Utah hasta el sur de Idaho y Nevada central. Su habitat en claras corrientes de 
montaña y manantiales es desusado para Lymnaeidae. S. caperata se encuentra en 
casi toda Norteamérica septentrional e incluye el area de S. montanensis en su distri- 
bución. Se encuentra en zanjas de irrigación y en aguas lodasas temporarias donde 
S. montanensis está ausente. Descripciones de habitats específicos y mapas de 
distribución geográfica (fósil y viviente) de las dos especies suministran datos sobre 
las diferencias no morfológicas entre las especies. La separación geográfica observada 
se debe, en parte, a las diferencias de exigencias ecológicas, pero probablemente 
también a la historia geológica de la región. S. pilsbryi se conoce solamente por el 
material original de una localidad en Utah occidental y no se dispone de datos ecoló- 
gicos respecto a esa especie. 

АБСТРАКТ 

ПРЕСНОВОДНЫЕ УЛИТКИ ñORFORk HINKLEYIA (LYMT:^AEmAE: STAGNICOLA EA 

ЗАПАДЕ СОЕЯИНЕННЫХ ШТАТОВ. 

Д. В. Тэйлор, Г. Дж. Волтэр и И. Б. Бёрч 

Подрод Hinkleyia до сих пор содержал только один вид Stagnicola cape- 
rata (Say) , но теперь он увеличен прибавлением вида S. montanensis (Ва - 
кег) , на основании различных конхиологических и анатомических данных, а вид 
S. pilsbryi (Hemphill) , исключительно из-за сходства раковины. Новые дан- 
ные позволяют пересмотреть диагноз подрода Hinkleyia , в котором имеется 
несколько отчетливых особенностей, но только на подродовом уровне. 

Шестнадцать экземпляров вида S. montanensis, сохраненных в алкоголе, 
были вскрыты. Анатомически они походили на S. caperata настолько близко, 
что нельзя было найти их отличительного свойства. 



TAYLOR, WALTER AND BURCH 281 

Оба вида отличаются своей раковиной. По форме, S. montanensis обыкно - 
венно более вытянута, а S. caperata более вздута, но эти качества перекры- 
вают друг-друга. Постоянным же и надежным различием между ними является их 
скульптура, а также плотность стенок. Сравнительно довольно заметные при- 
поднятые спиральные бороздки периостракума у S. caperata и блестящая глад- 
кая поверхность со спирально расположенными сериями крохотных полумесяцев 
у S. montanensis являются их постоянными отличиями. 

Насколько известно, эти два вида анатомически не отличны друг от друга 
и от типичных американских Stagnicola , за исключением: довольно развитый 
влагалищный мускул сфинктэр; большой дивертикулум, прикрепленный к прокси- 
мальному концу верхней простраты] довольно толстый и короткий чехольчик пе- 
ниса; сравнительно короткий и двусторонне-симметричный пенис с мускульным 
узлом посредине; и хорошо развитые серии заметно двузубчатых боковых ра - 
дульных зубчиков. 

По сравнению с типичными стагниколами, Hinkleyia (т. -е. S. montanensis 
и S. caperata ) имеет не столь заметно развитый влагалищный сфинктэр, замет- 
но толстый семепровод и более короткий пенис, с узлом, расположенным не по- 
средине, а ближе к дистальному концу его. Особенно заметна, суживающаяся 
к концу часть пениса пониже узла, ибо она короче, толще и не так отличается 
от проксимальной части, как в типичных стагниколах . У обоих видов чехольчик 
пениса необыкновенно толст и короток, а прострата особой формы и чрезвычай- 
но развита нижняя частьканала семепровода. Кроме того, в строении и окраске 
их анатомии, они очень сходны между собою и сильно отличны по наружному 
виду от остальных членов семейства прудовиков. Их тела сильно окрашены и 
их нога и щупальцы при жизни, вероятно, были узкими и удлиненными. 

Было также найдено, что S. m.ontanensis достигал половой зрелости при 
длине раковины от 6 до 7 мм. Можно полагать, что неизвестная нам масса 
яиц этого вида была тождественна с массой вида S. caperata, которая из из- 
вестных нам масс, отличается сравнительно большей толщиной отдельных яич - 
ных капсулей и тонкой малозаметной наружной туникой массы. 

Имеются анатомические указания на то, что виды, ранее причисленные к 
роду Stagnicola и включенные в подрод Nasonia, являются близкими KFossaria 
и, следовательно не родственны S. montanensis и S. caperata. Возможное 
родовое сходство между S, árctica с Hinkleyia скорее, чем с подродом Stag- 
nicola допускалось, но было отброшено на основании анатомических данных. 

Количество хаплоидных хромосом у S. m.ontanensis и у S. caperata равно 
18; У S. montanensis найдено 36 диплоидных хромосом. Эти количества харак- 
терны вообще для всех басомматофорных улиток. Детали гаметогенезиса включа- 
ют моноцентрический характер хромосом^ что, невидимому, свойственно всем 
прудовикам. Во время сперматогенезисаформируются обыкновенно 6 сперматогон- 
ных делений, за которыми следуют 2 мэтических деления. Поэтому сперматогон- 
ные клеточки встречаются в гнездах по 2, 4, 8, 16 и по 32, первичные спер- 
матоцисты - в гнездах по 64, а вторичные - в гнездах по 128 и сперматиды и 
сперма в гнездах по 256. 

Особенно цитологически интересно, что в гаметогенезисе обоих видов S. 
montanensis и S. caperata-, что ранее не было замечено в других прудовиках, 
это от 5 и до 7 больших хроматиновых тельца в каждом зародыше во время ран- 
них стадий первичного мэотического деления сперматогенезиса. Эти хромати- 
новые тельца являются, возможно, еще одним указанием на близкое родство 
этих двух видов. 

S. m.ontanensis широко распространен в западных Соединенных Штатах, в 
бассейне восточной части реки Колумбия и в северной части Великого Водного 
стока, от западной Монтаны и Юты и до южного Айдаго и центральной Невады. 
Место распространения этого вида в источниках и в чистых горных родниках 
так непохоже на экологию других прудовиков. S. caperata в настоящее время 
живет почти вез'де в Северной Америке и перекрывает ареал S. montanensis. 
Этот вид попадается в осушительных каналах и в мутных сезонных водах, где 
S. m,ontanensis не встречается. Описание ареалов и карты их географического 
распространения (живущих и ископаемых) этих двух видов дает данные, каса- 
ющиеся неморфологических различий между ними. Замеченные различия их ге- 
ографической обособленности существуют отчасти из-за их различных экологи- 
ческих требований и, возможно, что отчасти из-за геологической истории 
края. S. pilsbryi известен только из оригинального материала из одного 
только места в западной части штата Юта и экологических сведений о нем не 
имеется . 



THE DISTRESS SYNDROME IN TAPHIUS GLABRATUS (SAY) AS A REACTION 
TO TOXIC CONCENTRATIONS OF INORGANIC IONS 

Harold W. Harry^ and David V. Aldrich^ 

ABSTRACT 



In very low concentrations of toxic materials this snail shows normal behavior, ех-Д 
tending its body out of the shell, moving about, feeding and renewing its pulmonary air • 
bubble at the surface of the water. In higher concentrations of toxicants the snailV 
remains retracted in the shelL Between the concentration ranges of toxicants which 
produce retraction and those allowing normal behavior is a range of concentrations 
which induces a condition termed distress . The distressed snail is extended but unable 
to attach its foot, hence unable to move, feed or breathe atmosperic air. There is 
deterioration of the tentacles and elimination of sand grains from the stomach, but 
ciliary action and heart beat seem unaffected. Snails exposed for less than 24 hours 
*usually recover. 

Twenty-two ions were tested of which \^ produced distress. Ag, Cd and Cu ions 
did so between 0.050 and 0.100 ppm; Mn and Co ions only at 20 to 150 ppm and 30 to 
300 ppm respectively. Eight other ions were found to produce distress at concentrations 
intermediate between these extremes (Zn, Al, Ni, Ba, CrO^, Pb, Гез.Гез). The non- 
toxic range of concentrations of the remaining 9 ions is reported: Sn, Au, Sr, Li, 
M0O4, СГ2О7, up to 10 ppm; F up to 100 ppm and W0O4 and SO3 up to 150 ppm. The 
I extent of the range of concentrations which produces distress is directly proportional 
I to the minimal concentration of an ion which will produce sustained retraction. The 
I distress syndrome may be identical with relaxation produced by menthol and other 
¡organic compounds. 



In the search for molluscicides to 
use against pulmonate snails which serve 
as the intermediate hosts of trematodes, 
the sustained retraction of the animal in- 
\to the shell has been used as a criterion 
Ifor determining toxic concentrations 
(Nolan et. al., 1953). It is generally nec- 
essary to transfer the snails to a non- 
toxic medium to determine whether theyi 
subsequently show signs of life or decay. I 
During studies on the relation of water 
quality to the ecology of Та/)/ггм5 glabratus 



(Australorbis glabratus of authors)3 in 
Puerto Rico, we observed another type of 
response to toxicants. This was termed 
the "distres s synd rome" (Harry et al., 
1957,1958). It was evoked by concen- 
trations of ions too low to produce re- 
traction. These observations led to a 
systematic study of the production of this 
syndrome by very low concentrations of 
a variety of ions. 



^Rice University, Houston, Texas, U. S. A. 

2u. S. Fish and Wildlife Service, Ft. Crockett, Galveston, Texas, U. S. A. 

^For further particulars on the no menc lato rial relationships of the planorbids acting 
as intermediate hosts of Schistosoma mansoni, the reader is referred to Barbosa 
et al. (1961, Ann. Mag. Nat. Hist., Ser. 13, 4: 371-375), Wright (1962, Bull. Zool. 
Nomencl., pt. 1, 19: 39-41) and Walter (1962, Malacologia, 1: 115-137). ED. 



(283) 



284 



HARRY AND ALDRICH 



MATERIALS AND METHODS 

Glas^^axê^used in the experiments 
was washed in dilute HCl^ and rinsed in 
distilled water that had been passed 
through an ion exchange filter ("De- 
eminizer", Aloe Co.). The latter was 
done because the water from our metal 
still contained 0.050 to 0.070 parts per 
millón of copper, an amount sufficient to 
produce the distress syndrome. The 
filtered water contained l ess J han OjQlO 
ppni_ copper, which was the limit of the 
imethod of analysis (Huff, 1948), and which 
¡was innocuous to the snails. The distilled, 
^.demineralized water (DDW) was also used 
to prepare all stock solutions, the test di- 
lutions and the controls. Pyrex laboratory 
finger bowls (300 ml capacity) containing 
200 ml of the various dilutionsof the stock 
solutions were used for the tests. Adult 
snails recently collected in the field were 
/placed in DDW for half an hour before they 
'were transferred to the test solutions. 
Five snails of about 4-4 1/2 suture whorl 
\size were placed in each bowl of the test 
/solutions and in the control bowl of DWW. 
(AH tests were made at room temperature 
1(250 - 30° C). All ions studied (22) were 
tested in the concentrations shown in Fig. 
1, up to and including 10.0 ppm. In ad- 
dition, certain ions, as noted, were studied 
in those concentrations above 10.0 ppm 
listed in Fig. 1. The results were recorded 
at the end of 24 hours of exposure, and all 
experiments were repeated at least once. 

All stock solutions were prepared 
from reagen t grade chemicals. The cat- 
ions tested were prepared from the fol- 
lowing compounds: LÍSO4 H2O; А12(80^)з 
•I8H2O; MnS04-H20; FeS04.7H20; FeClg 
•6H2O; NÍS04-6H20; C0SO4.7H2O; CUSO4 
•5H2O; ZnS04-7H20; SrCl2-H20; AgS04 ; 
3CdS04-8H20; SnCl2-2H20; BaCl2; AUCI3 
.HCL.3H2O; and Pb(N03)2. Solutions of 
the anions were made from: NaF; Na2S03; 
К2СГО4; К2СГ2О7; NaMo04; andNaW04 
.2H2O. 

An artificial _stan dard reference 
waterJ^RW), used m some test, was based 
on the formula of Freeman (1953). We 
modified his formula to simulate the opti- 



mum quality of natural waters in which T. I 
glabratus was found to occur in Puerto 
Rico. (Harry et al., 1957). 

RESULTS 

A normally behaving snail extends 1 
from the aperture of the shell and attaches 
itself to the surface of the bowl with its foot. 
It is usually moving about and quite capable 
of feeding and visiting the surface to ex- 
change the air in the pulmonary cavity. 
The typically distressed snail lies on 

jthe bottom of the bowl with the с ephalopedal 

Imass extended. It is unable to attach the 
foot to the substrate although it frequently 
applies the anterior end momentarily, in an 

xapparent attempt to do so. After several 
hours the tentacles usually become swollen 
at their bases, and show extensive sloughing 

^of cells distally. Movement of the foot 
gradually becomes more feeble and less 
frequent, but at later stages a series of 
spasmodic contractions of the body stalk 
дге sometimes seen. Although muscular 
action may later cease, ciliary activity on 

ttie external surface of the body and in the 
ulmonary cavity seems unaffected, at 
least during the first 24 hours of exposure. 
The heart continues to beat while the snail 
is in distress, though at apparently a 
slower rate. There is a tendency for the 
distressed snail to eliminate most of the 
jsand grains from the stomach by defe- 
I cation. Normal snails, once supplied with 
sand, retain the grains in the stomach for 
weeks, if deprived of sand in their ex-^ 
ternal environment. 

Like the retracted snails, those in , 
distress are unable to feed, or crawl to thejj 
surface to renew the air bubble in the ( 
pulmonary cavity. There is no manifest 
difference in the distress syndrome as 
(produced by one ion and that produced by 
I another. Once distressed, snails may 
remain in this state for several days, if 
left in the medium which produced the phe- 
nomenon. Snails which have been dis- 
tressed 24 hours or less will usually re- 
cover within a few hours if transferred to 
a large volume of non-toxic medium, such 
as DDW. Attachment of the foot is fol- 



DISTRESS SYNDROME IN TAPHIUS GLABRATUS 



285 



lowed by locomotion and the snail can again 
feed and crawl to the surface to "breathe". 

/The tentacles regenerate within a few 

' weekSo 

In each of the 22 ions tested, the com- 
panion ion present was known to be non- 
toxic at the concentrations used, from the 

|report of Deschiens (1954) and our own un- 
ipublished work. 

In the case of 9 ions, not even the 
higher concentrations tested produced 
distress or retraction, as follows: 



Fig. 1 shows the results obtained 
from the _13 more tox ic ions. With the ex- 
ception of lead and divalent iron, the effect 
of the various concentrations was well de- 
fined. In 5.0 and 10.0 ppm of lead, most 
of the snails were normal, but one or two 
showed sustained retraction. Divalent iron 
produced the same mixed reaction in 
concentrations of 10.0 to 100.0 ppm, and 
the reaction was not uniform until the 
concentration reached 150.0 ppm. 

DISCUSSION AND CONCLUSIONS 



ions: 

tin 

gold 

strontium 

lithium 

molybdate 

dichromate 

fluoride 

tungstate 
sulfite 



still non -toxic 
at: 



10.0 ppm 

100.0 ppm 
150.0 ppm 



The ions in Fig, 1 are arranged in 
the order of their increa sing toxicity. If 
the concentrations beexpressed in mo- 
larity, instead of parts per million, ap- 
proximately the same series would result] 
as when the ions are ranked as in Fig. 1; 
Cd, Ag, Cu, Zn, Ni, Pb, Ba, Al, СГО4, Fe, 
Mn, Co. It is notable that the three most 
toxic ions, cadmium, silver, and copper, 
produced distress at 0.05 to 0.1 ppm, or4| 
to 6 X 10"'^ M, under these experimental ' 
conditions. 

From the data under consideration, 
it appears that the ^ower the_concentration 



parts 

per 

millón 

300 

150 

100 

80 

40 

30 

20 

10 

5 

1 

0.100 

0.050 

0.005 

DDW 



























D 


















R 


R 


R 


D 


D 


















R 


R 


N(D) 


D 


D 


















R 


R 


N(D) 


D 


D 


















R 


D 


N(D) 


D 


D 












R 






R 


D 


N(D) 


D 


D 












D 






R 


D 


N(D) 


D 


N 


R 


R 


R 


R 


R 


D 


D 


D 


N(R) 


D 


N(D) 


N 


N 


R 


R 


R 


R 


D 


D 


D 


D 


N(R) 


N 


N 


N 


N 


R 


R 


R 


D 


D 


D 


N 


N 


N 


N 


N 


N 


N 


D 


D 


D 


D 


N 


N 


N 


N 


N 


N 


N 


N 


N 


D 


D 


D 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 


N 



Ag Cd Cu Zn Al Ni Ba СГО4 Pb Гез Fe2 Mn Co 



FIG. 1. Reaction of Taphius glabratus after 24 hours exposure to the various concen- 
trations of 13 of the more toxic ions shown. 



R, sustained retraction 

D, distressed 

N, normal (extended, attached, usually crawling, no tentacular damage); 

DDVT, distilled demineralized water 



286 



HARRY AND ALDRICH 



jof an ion which produces retraction, the 
¡narrower the range of concentrations 
which produces distress, and the higher the 
jminimal concentration which produces re- 
traction, the broader the range of concen- 
trations which produces distress. Whether 
this is generally true, or only coincidence 
in the series of ions tested, remains tobe 
demonstrated. Seven of the 13 ions of Fig. 
1 seem to substantiate this hypothesis. 
Unfortunately, circumstances did not allow 
us to ascertain the minimal concentration 
\of barium, Chromate, manganese or cobalt 
ions which will presumably produce re- 
tractions. 

Lead may be an exception to the rule 
that a range of concentrations which will 
/produce distress occurs just below the 
•4 I minimal concentration which will produce 
! retraction. Perhaps the presence of or- 
ganic materials such as mucus or feces 
was instrumental here in inhibiting the 
3< toxic action of this ion. 

That extrinsic factors may limit the 
toxic action of copper is well known, and 
usually attributed to organicmaterial in the 
environment (Magalhaes Neto et al., 1953; 
Lacrange, 1952). Our experiments with 
zinc have shown that organic material may 
not be the only factor which modifies the 
inability of the metal to produce distress. 
A layer of zinc powder covered the bottom 
of the bowls that contained either 200 ml 
of DDW or of SRW-. In the latter the snails 
showed normal activity, made trails 
through the powder, and zinc granules 
could easily be demonstrated in the di- 
gestive tract and even in the liver lumen. 
In DDW, however, the snails soon showed 
distress which persisted for the 24-hour 
period of the test. Zinc granules were not 
found in their digestive tracts. Presuma- 
jbly the amount of organic material in each 
/test lot was the same, and derived chiefly 
y from the mucus and waster products of the 
/ snails. 

Symptoms of the distress syndrome 

have been noted only occasionally in the 

Jitliterature (e.g. Nolan et al. 1953:719), 

but have not previously been recognized 

>tas symptomatic with regards to toxicity. 

Certain concentrations of some organic 



compounds also produce distress. Michel- 
son (1957) has reported that minute quanti- 

•^ties or urethane or nicotine sulfate produce 
similar reactions in this snail. Chemin 
(1959) has reported several antibiotics \ 
which seem to produce similar behavior, 
and he noted that the toxic effect of some 
of these was reduced by the presence of 
commercial potting soil (surely high in 
organic compounds) or calcium, but that 
magnesium seemed to have no detoxifying 
effect. 

The distress syndrome grossly re4 
sembles the response evoked by menthol,! 
which is frequently used by malacologistsj 
for "relaxing" fresh water snails before 
fixing them for anatomical studies. Van 
der Schalle (1953) has reported the effect 
of nembutal in producing similar relax- 
ation. ' 
The actual physiological mechanism 
involved in the syndrome of distress is 

^unknown, though it is apparently a neuro- 
muscular phenomenon. Ciliary activity, 
notoriously autonomous and difficult to 

narrest by poison, seems unaffected by the 
ions we studied. Distress is a response, 
which should receive much moreattentionl 
than it has in the past, not only for the' 
light it may shed on the general subject of 
4, ♦•♦the physiology of fresh water organisms, 
but specifically for understanding thej 
actions of moUuscicidesf 

LITERATURE CITED 

CHERNIN, E,, 1959, Notes on the effects 
of various antibiotics on Australorbis 
glabratus. J. Parasit. 45: 268. 

DESCHIENS, R. 1954, Incidence de la 
mineralization de l'eau sur les mol- 
lusques vecteurs des bilharzioses. 
Conséquences pratiques. Bull. Soc. 
Path. Exot. 47: 915-929. 

FREEMAN, L., 1953, A standardized 
method for determiningtoxicity of pure 
compounds to fish. Sewage and In- 
dustrial Wastes 25: 845-848. 

HARRY, H. W., B. G. CUMBIE and J. 
MARTINEZ DE JESUS, 1957, Studies 
on the quality of fresh waters of Puerto 
Rico relative to the occurrence of 



DISTRESS SYNDROME IN TAPHIUS GLABRATUS 



287 



Australorbis glabratus. Amer. J. 1 гор. 
Med. Hyg. 6: 313-322. 

HARRY, H. W. and D. V. ALDRICH, 1958, 
Ihe ecology of Australorbis glabratus 
in Puerto Rico. Bull. Wld. Hlth. Org. 
18: 819-832. 

HUFF, L. С, 1948, А sensitive field test 
for heavy metals in water. Econ. Ge- 
ology, 43: 675-684. 

LAGRANGE, E., 1952, A propos de V 
action oligodynamique sur les mollus- 
ques pulmones en particulier et sur la 
faune aquatique en général. Arch. Inter- 
nat. Pharmacodyn. Thér. 91: 185-193. 

MAGALHAES NETO, В. M., A. M. DE 
ALMEIDA, J. С DE MORAES and O. 
B. CALADO, 1953, Factors that 



influence the molluscacide activity of 

copper under laboratory conditions. 

Pub. Avulsas Inst. Aggeu Magalhaes 

(Recife, Brazil), 2: 103-113. 
MICHELSON, E. П., 1957, Studies on the 

biological control of schistosome- 

bearing snails. Parasitology (British). 

47: 413-426. 
NOLAN, M. O., H. W. BOND and E. R. 
MANN, 1953, Results of laboratory 
screening tests of chemical compounds 
for moUuscicidal activity. Amer. J. 
Trop. Med. Hyg. 2: 716-752. 
VAN DER SCHALIE, H., 1953, Nembutal 
as a relaxing agent for moUusks, 
Amer. Midland Naturalist, 50:511-512. 



ZUSAMMENFASSUNG 

NOT-SYNDROM IN TAPHIUS GLABRATUS (BASOMMATOPHORA: PLANORBmAE) 
INFOLGE TOXISCHER KONZENTRATIONEN ANORGANISCHER IONEN, 



In sehr niedrigen Konzentrationen wässriger Lösungen toxischer Substanzen verhält 
sich diese Schnecke normal, d.h. sie streckt ihren Körper aus der Schale hervor, 
kriecht umher, frisst und erneuert an der Wasseroberfläche den Luftgehalt ihrer Lunge. 
In höheren Konzentrationen bleibt sie völlig in ihrer Schale zurückgezogen. Zwischen 
den Grenzwerten derjenigen Konzentrationen die Retraktion verursachen und solchen 
die ein normales Verhalten zulassen, liegen diejenigen welche einen Zustand hervorrufen 
den wir als Not-Syndrom bezeichnen wollen. Eine Schnecke in Nöten streckt zwar 
ihren Fuss aus der Schale hervor, ist jedoch unfähig damit zu fassen und, daher, weder 
imstande sich fortzubewegen,noch sich zu ernähren oder atmosphärische Luft einzuatmen. 
Es tritt weiters eine Degeneration der Tentakeln ein und die im Magen befindlichen 
Sandkörner werden ausgestossen; die Zilienbewegungen sowie der Herzschlag scheinen 
jedoch unbeeinflusst. Schnecken, die syndromauslösenden Konzentrationen für weniger 
als 24 Stunden ausgesetzt waren, erholen sich meist. 

Auf ihre Wirksamkeit hin wurden 22 Ionen untersucht, von denen 13 den Notzustand 
hervorriefen. Bei Ag, Cd und Cu Ionen war dies schon bei Konzentrationen zwischen 
0.050 und 0.100 1 eilen pro Million der Fall; bei Mn und Co hingegen erst zwischen 20 
und 150 T./Mill. bzw. 30 und 300 l./Mill. Bei Konzentrationen die zwischen diesen 
Extremen liegen verursachten folgende 8 Ionen das Syndrom: Zn,^Al, Ni, Ba, СГО4, Pb, 
Fe2, Fe3. Die 9 restlichen Ionen waren in den untersuchten Konzentrationen nicht 
wirksam, und zwar: Sn, Au, Sr, Li, M0O4, СГО2О7, bis 10 T./Mill.; F bis 100 T./Mill. 
sowie Wo04und SO3 bis 150 T./Mill. Die Breite des Wirkungsbereiches jener Konzen- 
trationen auf welch, bei einem gegebenen Ion, ein Notzustand erfolgt ist seiner zu 
andauernder Retraktion führenden Mindestkonzentration direkt proportional. Das Not- 
Syndrom ist möglicherweise identisch mit der von Menthol und anderen organischen 
Verbindungen ausgelösten Entspannung. 



288 HARRY AND ALDRICH 

RÉSUMÉ 

LE SYNDROME DE DETRESSE CHEZ TAPHIUS GLABRATUS (BASOMMATOPHORA: 
PLANORBIDAE) CAUSE PAR DES CONCENTRATIONS TOXIQUES 
D'IONS INORGANIQUES. 

Exposé à de très faibles concentrations de substances toxiques en solution aqueuse, 
ce mollusque se comporte normalement, c'est à dire qu'il étend son corps hors de sa 
coquille, rampe, se nourrit et renouvelle à la surface de l'eau l'air de sa cavité pulmo- 
naire. En concentrations plus élevées il reste rétracté dans sa coquille. Entre les 
limites des concentrations qui provoquent la rétraction et celles qui permettent encore 
un comportement normal, se trouvent celles qui amènent un etat que nous appelons 
détresse. Le pied d'un mollusque en détresse est étendu hors de sa coquille, mais il 
est incapable d'adhérer, de sorte que l'animal ne peut se nourrir ni respirer l'air atmos- 
phérique. Ses tentacules se détériorent, les grains de sable contenus dans son estomac 
sont rejetés, mais ni l'action ciliaire ni les battements du coeur ne semblent affectés. Le 
mollusque, d'habitude, se remet, s'il a été soumis moins de 24 heures à ces conditions. 

Vingt-deux ions furent essayés, dont 13 déclenchèrent le syndrome. Les ions d'Ag, 
Cd et Cu provoquèrent la détresse déjà entre les concentrations de 0.050 et 0.100 
parties par million, tandis que ceux de Mn et Co ne la firent apparaître qu'entre 20 et 
150 ppm et 30 et 300 ppm respectivement. Huit autres ions furent efficaces à des 
concentrations intermédiaires entre ces extrêmes: Zn, Al, Ni, Ba, СГО4, Pb, Fe2, Feß, 
Les 9 ions restants ne donnèrent aucune réaction dans les échelles de concentration 
essayées, soit: Sn, Au, Sr, Li, M0O4, СГ2О7, jusqu'à 10 ppm; F jusqu'à 100 ppm ainsi 
que W0O4 et SO3 jusqu'à 150 ppm. L'étendue de l'intervalle de concentrations provo- 
quant le syndrome pour un ion donné est directement proportionelle à sa concentration 
minimale donnant lieu à une rétraction durable. Le syndrome de détresse pourrait 
bien être identique au relâchement causé par le menthol et par d'autres composés 
organiques. 



RESUMEN 

SÍNDROME DEPRESIVO EN TAPHIUS GLABRATUS (SAY) (BASOMMATOPHORA: 

PLANORBIDAE) COMO REACCIÓN A CONCENTRACIONES TOXICAS 

DE IONES ORGÁNICOS 

En concentraciones mínimas de materiales tóxicos este caracol muestra com- 
portamiento normal, extendiendo su cuerpo fuera de la concha, moviéndose, alimen- 
tándose y renovando su burbuja pulmonar en la superficie del agua. En mayores 
concentraciones tóxicas, el caracol permanece retraído dentro de la concha. Entre 
las condiciones que producen retracción y las que permiten comportamiento normal, 
existe una serie de concentraciones que inducen una condición depresiva: el animal se 
extende pero no es capaz de afirmar el pie y, por consiquiente, de reptar, alimentarse 
o respirar aire atmosférico. Sobreviene deterioración de los tentáculos y eliminación 
de granos de arena del estómago, pero la actividad ciliar y la pulsación cardíaca no 
parecen afectadas. Los caracoles sometidos a esta condición por menos de 24 horas 
generalmente se recuperan. 

Se probaron 22 iones, de los cuales 13 produjeron estados de depresión. Los iones 
Ag, Cd y Cu produjeron tal efecto entre 0.050 y 0.100 ppm; Mn y Co solamente entre 
20 y 150 ppm, y 30 y 300 ppm, respectivamente. Ocho otros iones produjeron depresión 
en concentraciones distribuidas entre esos extremos (Zn, Al, Ni, Ba, CrÜ4, Pb, Fe^^ 
Еез). La gradación no tóxica de las concentraciones de los 9 iones restantes fué la 
siguiente: Sn, Au, Sr, Li, M0O4 y СГ2О7, hasta 10 ppm; F, hasta 100 ppm; W0O4 y SO3, 
hasta 150 ppm. La amplitud del rango de concentraciones que producen depresión 
es directamente proporcional a la concentración mínima de un ion que produjera 
retracción continua. El síndrome depresivo sería quizás idéntico al efecto relajante 
producido por mentol y otros compuestos orgánicos. 



DISTRESS SYNDROME IN TAPHIUS GLABRATUS 289 

АБСТРАКТ 

СИНДРОМЫ ТРЕВОГИ в ГЛРЯ/г75 GLABHATÎ/S (SAY) ,(BASOMM ATO PHORA PLANOR- 

ВШАЕ) КАК РЕАКЦИЯ К ЯДОВИТЫМ КОНЦЕНТРАТАМ НЕОРГАНИЧЕСКИХ ИОНОВ 

Гарольд В. Харри и Давид В. Олдридж 

В очень слабых растворах ядовитых материалов, эта улитка реагирует 
нормально, вытягивая тельце из раковины, двигаясь, питаясь и возобновляя 
свой пузырек воздуха на поверхности воды. В случаях же усиления раствора 
токсинов, действие которых не прерывает нормальный образ действий, и бо- 
лее сильными, есть определенная точка, которая является сигналом опасности. 
В таком состоянии улитка вытягивается, но не может прикрепить ногу к по - 
верхности и, следовательно, не в состоянии двигаться, питаться или дышать 
атмосферным воздухом. Начинается порча щупальцев и выталкивание песчинок 
из желудка, но ресничное действие и сердцебиение кажутся незатронутыми. 
Улитки, подверженные такому действию менее 24 часов, обыкновенно выздорав- 
ливают . 

Двадцать два иона были испробованы, из которых 13 дали реакцию опас- 
ности. Ag, Cd, и Cu ионы дали такие результаты между 0.050 и 0.100 ррт; 
Мп и Со ионы от 20 и до 150 ррт - соответственно. Восемь других ионов 
вызвали сигналы опасности в концентратах между этими крайностями (Zn, Al, 
Ni, Ва, Cr04, Pb, Fe2, Feß). Вполне безопасными оказались растворы 
остальных 9 ионов: Sn, Au, Sr, Li, M0O4, СГ2О7, до 10 ppm; F и до 100 
ррт mWo04, и SO3 до 150 ррш. Таким образом, сила концентрата, вызыва- 
ющая реакцию опасности, находится в прямой пропорции к минимуму концентра- 
ции иона, которую может вынести улитка. Синдром опасности может быть тож- 
дественным с расслаблением, которое производят ментол и другие органичес - 
кие составы. 



I 



THE EFFECTS OF ECHINOPARYPHIUM bARVAE ON THE STRUCTURE 
OF AND GLYCOGEN DEPOSITION IN THE HEPATOPANCREAS OF 
HELISOMA TRIVOLVIS AND GLYCOGENESIS IN THE PARASITE LARVAE 1 

Thomas C. Cheng 

Department of Biology, Lafayette College 

Easton, Pennsylvania, U. S. A. 

ABSTRACT 



Histological examinations of the hepatopancreatic tissues of the planorbid snail 
Helisoma trivolvis invadedby the rediaeof the trematode Echinoparyphium sp. revealed 
that the damage to host cells can be attributed primarily to ingestion and secondarily 
to histolysis by redial digestive enzymes which are egested along with cellular debris. 
Morphological evidence of the secondary lytic activity is furnished by lysed cells in 
areas where there are heavy concentrations of cellular debris identical to that found in 
the redial intestinal cecum. The presence of rediae in the hepatopancreas induces the 
hypersecretion of yellowish globules by hepatic cells. Histochemical studies revealed 
that less glycogen is removed from intact hepatopancreatic cells of H. trivolvis infected 
with the rediae of Echinoparyphium sp. than in instances where the sporocysts of 
Glypthelmins pennsylvaniensis are present. These rediae are believed to acquire 
their carbohydrate requirements primarily through the direct ingestion of the host's 
glycogen-containing hepatopancreatic cells rather than through the absorption of mono- 
saccharides which have resulted from the breakdown of glycogen in intact cells, as do 
the sporocysts. 

The redial body wall and oral sucker are the primary sites of glycogen storage in 
this larval stage. However, not all the PAS-positive material in the redial wall is 
glycogen, since it is only partially digested with diastase. The sites of glycogen 
deposition in developing cercariae include the sucker primordia, the primordia of the 
pharynx, esophagus, intestinal ceca, and the two conspicuous lateral collecting tubules 
of the excretory system. In addition, parenchymal cells also include glycogen, except 
for a few large cells, probably developing cystogenous glands, which include PAS- 
positive material that is only partially digested when treated with diastase. Compara- 
tively little glycogen is present in cercarial tails where the heaviest concentration is 
found along the "core" of each tail. This limited occurrence of glycogen might be 
explained by the lack of a prolonged physiological need for carbohydrates in this tempo- 
rary organ. It is believed that carbohydrate metabolism of stored glycogen serves as 
the primary means for energy production in these intramoUuscan larvae since, although 
fatty acids are present, the essentially anaerobic environment in the hepatopancreas 
does not lend itself to energy production through lipid metabolism. 



INTRODUCTION 

The various types of known structural 
and physiological changes effected by 
trematode larvae on their moUuscan hosts 
have been reviewed in earlier papers 
(Cheng and Snyder, 1962 a, b). This study 
is concerned with the structural and 
chemical alterations in the hepatopancreas 



of the planorbid snail Helisoma trivolvis 
(Say) infected with the rediaeof an echino- 
stome of the genus EchinoparyphiumDietz. 
Aspects of this study have been reported 
in a preliminary abstract (Cheng, 1962). 
The effects of trematode rediae on their 
molluscan hosts have been studied by 
Hurst (1927), F. G. Rees (1934), W. J. 
Rees (1936), Cheng and James (1960), 



iThis research was supported by Grants E-3443, E-3443C1, and AI 3443-03 from the 
Institute of Allergy and Infectious Diseases, National Institutes of Health, U. S. Public 
Health Service. It is a contribution from the Laboratory of Parasitology and Inverte- 
brate Zoology, Jenks Biological Laboratories, Lafayette College. 

(291) 



292 



T. С. CHENG 



and pictured by Malek (1962). These 
authors reported local histolysis, me- 
chanical disruptions, decrease in hepato- 
pancreatic glycogen, and indirect damage 
to the digestive gland resulting from rediae 
located outside of that gland in the ad- 
jacent gonads. This present study serves 
to confirm some of the earlier findings but 
more important, to present a new hypothe- 
sis as to the mechanism involved in local 
histolysis of hepatopancreatic cells. 
Furthermore, presented below is a com- 
parison and a possible explanation for the 
differences which exist in the amount of 
the host's hepatopancreatic glycogen which 
is removed when rediae or sporocystsare 
present. 

MATERIALS AND METHODS 

During the summer of 1962, over 500 
specimens of Helisoma trivolvis were 



collected from Green Pond, Bethlehem, 
Northampton County, Pennsylvania. Twen- 
ty per cent of these were found to be in- 
fected with the rediae of an echinostome 
trematode. The parasite could not be 
identified definitely by its redial and 
cercarial stages, although it was suspected 
that these represented stages in the life 
cycle of a member of the genus Echino- 
paryphium. Therefore, experiments were 
conducted to determine the life history of 
this trematode so as to obtain adults 
which could be identified more readily. 
While dissecting the snails' internal 
organs to determine the primary site of 
infection by rediae, a number of encysted 
metacercariae were found loosely attached 
to the inner surface of the shells, to the 
alimentary tract, and to the tunica propria 
of the hepatopancreas. Such metacer- 
cariae, removed from their cyst walls, 
showed a striking resemblance to the 



EXPLANATION OF PLATES 

AL, acinar lumen of hepatopancreatic tubule; CF, cell fragments scattered in between 
rediae; DCER, developing cercariae; FRIC, cell fragments in redial intestinal cecum; 
HCG, globules secreted by hepatic cells; IHC, intact hepatopancreatic cells; LHC, dis- 
lodged hepatopancreatic cells; PASCT, PAS+ material associated with lateral collecting 
tubule of excretory system; PASG, PAS+ material in parenchymal gland cells; PASHC, 
PAS+ material in hepatopancreatic cell; PASI, PAS+ material in intestinal cecal wall of 
redia; PASIC, PAS+ material intermingledwithcellular debris in lumen of redial cecum; 
PASP, PAS+ material associated with primordium of sucker; PASRW, PAS+ material 
associated with redial wall; RED, redia; RW, redial wall; ТА, cercarial tail; YDCER, 
young developing cercarla. 

PLATE I 



FIG. 1. Photomicrograph of cross-section of redia of Echinoparyphium sp. in hepato- 
pancreas of Helisoma trivolvis showing cellular debris in intestinal cecum. Delafield's 
hematoxylin. (40x obj.) 

FIG. 2. Photomicrograph of cross-section through hepatopancreas of infected Я. tri- 
volvis showing numerous rediae enclosing developing cercariae and a clump of cell 
fragments. Mallory's triple. (40x obj.) 

FIG. 3. Photomicrograph of cross-section through hepatopancreas of infected H. tri- 
volvis showing large number of light (yellowish) hepatic cell secretions and dislodged 
hepatopancreatic cells. Mallory's triple. (40x obj.) 

FIG. 4. Photomicrograph of cross-sections of portions of several hepatopancreatic 
tubules of uninfected Я. trivolvis showing rich distribution of PAS+ material in cells. 
PAS method. (40x obj.) 



EFFECTS OF ECHINOPARYPHIUM ON HELISOMA 



293 



PLATE I 




294 



T. С. CHENG 



emitted cercariae in the number and ar- 
rangement of spines forming the collar. 

In order to confirm that the metacer- 
cariae found were of the same species as 
the cercariae, uninfected laboratory 
raised H. trivolvis and uninfected Physa 
gyrina (Say),collectedfrom another locale, 
were placed in finger bowls together with 
individual infected H. trivolvis. Both 
species of snails thus exposed harbored 
encysted metacercariae within 24 hours, 
which proved that the metacercariae had 
developed from the emitted cercariae. 

Encysted metacercariae were fed to 
laboratory raised Japanese quails, Co- 
tumix coturmx japónica, and from their 
small intestine sexually mature adult 
worms were recovered on the 8th day. 
Examination of stained and mounted adult 
specimens verified that the trematode was 
a member of the genus Echinoparyphium, 
although it could not be readily relegated 
to any of the known species. 

After successful identification of the 
parasite, 20 infected and 5 uninfected 
snails were removed from their shells 
and prepared for histological and histo- 
chemical studies. Ten of the infected 
snails were fixed in Carnoy's Fixative 
(6:1:1), embedded, and sectioned at 8 
microns, some in cross-section and others 
in longitudinal-section. Alternate slides 
of these were stainedwithMallory's triple 
connective tissue stain and Delafield's 
hematoxylin respectively. The remaining 



10 infected snails were fixed in Zenker's 
Fixative, embedded, and sectioned in the 
same manner. Alternate slides of this 
series were exposed to the periodic acid- 
Schiff (PAS) reaction for glycogen, ac- 
cording to the procedure given earlier 
(Cheng and Snyder, 1962a); the remaining 
were exposed to 0.5% diastase and the 
PAS reaction to serve as controls. Three 
of the uninfected snails were fixed in 
Zenker's, sectioned, and treated with the 
PAS reaction, with alternating slides 
treated with diastase to serve as controls. 
The remaining 2 uninfected snails were 
similarly fixed, sectioned, and stained 
with one or the other of the two histo- 
logical stains given. 

RESULTS 

Histological: The hepatopancreas of 
Helisoma trivolvis is the primary site 
of infection by the rediae of Echino- 
paryphium sp. There is extensive damage 
of the hepatopancreatic tubules. Critical 
examinations revealed that most of the 
intact cells are severed and removed, 
since large areas of the hepatopancreas 
at all levels are devoid of visible cells; 
resulting pockets are packed with rediae 
which enclose developing cercariae. Frag- 
ments of the hosts' hepatopancreatic cells 
are present in the intestinal ceca of the 
rediae (Plate 1, Fig. 1). In addition, clumps 
of similar cell fragments are found inter- 



PLATE П 



FIG. 1. Photomicrograph of cross-section of a single hepatopancreatic tubule of 
infected H. trivolvis showing less PAS+ material in cytoplasm than that observed in 
Plate 1, Fig. 4. PAS method. (40x obj.) 

FIG. 2. Photomicrograph of cross-section through a redia of Echinoparyphium sp. 
showing PAS+ material associated with redial wall, developing cercariae, cecal wall, 
and cecal contents. PAS method. (40x obj.) 

FIG. 3. Photomicrograph of section through a redia showing PAS+ material associated 
with area of presumptive sucker and the absence of PAS+ material in young differenti- 
ating germ balls. PAS method. (40x obj.) 

FIG. 4. Photomicrograph of cross-section through a redia showing PAS+ material 
associated with lateral collecting tubules of excretory system of cercarla and lack of 
PAS+ material in young developing cercarla. PAS method. (40x obj.) 



EFFECTS OF ECHINOPARYPHIUM ON HELISOMA 



295 



PLATE II 




PASP 




шщ 






PASCT % 






YDCER 








i 



296 



T. С. CHENG 



mingled with intact host cells outside of 
the rediae in the hepatopancreas (Plate 1, 
Fig. 2). These aggregates of cell frag- 
ments are believed to come from the 
redial intestinal ceca because a con- 
siderable amount of dark, almost black, 
granules are intermingled among the 
cellular debris. These granules are also 
present in the ceca and appear charac- 
teristically to be associated with ingested 
cells which have been subjected to 
digestion. The blackish coloration of these 
granules is not due to differential staining, 
since their appearance is identical in 
sections stained both by Mallory's and 
Delafield hematoxylin. Such aggregates, 
when observed outside of the rediae, are 
most plentiful in areas where large 
numbers of rediae are found. Intact cells 
in the presence of cell fragments 
commonly show symptoms of lysis. 

A large number of irregularly rounded 
yellowish globules are present in the prox- 
imity of the few remaining intact cells 
(Plate 1, Fig. 3). Such globules, in lesser 
quantity, normally are found intracyto- 
plasmically in certain hepatopancreatic 
cells of uninfected snails and undoubtedly 
represent the liver cell globules of Bar- 
furth (1883). The yellowish coloration 
of these globules is apparent in sections 
stained both by Mallory's and Delafield 
hematoxylin. 

Histochemical: The hepatopancreatic 



cells of uninfected Яе/г5ота trivolvis are 
characteristically rich in glycogen as 
determined by the PAS reaction. The 
stored glycogen appears as finely granular 
PAS-positive material more or less evenly 
distributed in the cytoplasm, usually with 
a slightly greater concentration towards 
the luminal portion of each cell forming 
the acinus (Plate I, Fig. 4). 

In Я. trivolvis infected with Echino- 
paryphium rediae, there is a slight de- 
crease in the amount of stored glycogen 
in the hepatopancreatic cells (Plate II, 
Fig. 1). The decrease is definitely not as 
drastic as is the case in H. trivolvis 
infected with sporocysts of Glypthelmins 
pennsylvaniensis Cheng (see Cheng and 
Snyder, 1962a). 

The redial wall is strongly PAS- 
positive, as are the oral sucker, the 
intestinal cecal wall, and the cecal contents 
(Plate II, Fig. 2). The PAS-positive 
materials found within the redial wall, 
however, are not all glycogen; in diastase- 
treated control sections, although there is 
a noticeable decrease in the amount of 
PAS-positive material in the redial wall, 
some of it persists. 

There is no PAS-positive material in 
the bodies of germ balls and very little 
in young differentiating cercariae (Plate 
II, Figs. 3, 4). Large deposits of PAS- 
positive material appear at the time the 
suckers begin differentiating. Atthattime, 



PLATE Ш 



FIG. 1. Photomicrograph of section through redia showing PAS+ material associated 
with area of presumptive sucker and with lateral collecting tubules of cercarial 
excretory system. PAS method. (40x obj.) 

FIG. 2. Photomicrograph of section through fully developed cercarla in brood chamber 
of redia showing PAS+ material associated with parenchymal gland cells. PAS method. 
(40x obj.) 

FIG. 3. Photomicrograph of section through fully developed cercarla showing PAS+ 
material associated with dorsally located parenchymal gland cells. PAS method. (40x 
obj.) 

FIG. 4. Photomicrograph of longitudinal section of fully developed cercarla showing 
PAS+ material associated with parenchymal gland cells and slight amount of PAS+ 
material associated with cercarial tail. PAS method. (40x obj.) 



EFFECTS OF ECHINOPARYPHIUM ON HELISOMA 



297 



PLATE III 




RW 
/ 




PAS6 




3 




298 



T. С. CHENG 



the sucker primordia are extremely rich 
in PAS-positive material (Plate II, Fig. 3; 
Plate III, Fig. 1). In addition, the primordia 
of the pharynx, esophagus, intestinal ceca, 
and the two conspicuous lateral collecting 
tubules of the excretory system are also 
rich in PAS-positive material (Plate II, 
Fig 4; Plate III, Fig. 1). When observed 
in cross-section, a few large parenchymal 
cells lying along the dorsal body wall 
include heavy concentrations of homo- 
geneously PAS-positive material (Plate 
III, Figs. 2, 3, 4). These undoubtedly 
represent gland cells, probably cysto- 
genous glands. The remaining parenchy- 
mal cells also include finely granular 
PAS-positive materials, but these are not 
as heavily concentrated. 

Comparatively small amounts of PAS- 
positive material are present in the cer- 
carial tails where the heaviest concen- 
tration is seen along the "core" of each 
tail (Plate III, Fig. 4). 

Practically all of the PAS-positive 
material found in cercariae is glycogen, 
since such material was not observed in 
in diastase -treated sections, except in the 
large gland cells situated in the parenchy- 
ma. Although the intensity of PAS-positive 
staining in these cells is reduced con- 
siderably when treated with diastase, these 
cells were still definitely PAS-positive 
even after 45 minutes of digestion. 

DISCUSSION AND CONCLUSIONS 

The life history pattern among Echino- 
paryphium spp. is well known. Reich 
(1927) reported that the cercariae of 
Echinoparyphium aconiatum Dietz, es- 
caping from Stagnicola palustris (Müller) 
(=Lymnaea palustris), enter and encyst 
in the same and other species of fresh- 
water gastropods. McCoy (1927) and 
Najarían (1954) reported that the meta- 
cercariae of E. flexum (Linton) were 
found in Helisoma trivolvis and Lymnaea 
lacustris (Leach) after the cercariae had 
escaped from Physa integra (Haldeman) 



or S. palustris. Various authors (Tsuch- 
imochi, 1924; Mathias, 1926, 1927; Harper, 
1929; Suzuki, 1932) have demonstrated 
that E. recurvatum (Linstow) can utilize 
a gastropod as the second intermediate 
host. This pattern among Echinopary- 
phium spp., which includes two molluscan 
intermediate hosts, is upheld by the 
species under consideration. 

It is quite evident that the rediae of 
Echinoparyphium do cause drastic damage 
to the hepatopancreas of Helisoma tri- 
volvis. The primary method of cell 
destruction and removal appears to be 
through direct ingestion. This interpre- 
tation is borne out by the presence of 
large quantities of cellular debris found 
in the intestinal ceca of the rediae and 
the severe mechanical damage visible in 
those areas of the digestive gland where 
the heaviest concentrations of rediae are 
found. Direct ingestion of the molluscan 
host's hepatopancreatic cells have been 
reported by Cheng and James (1960). 
Unlike Hurst (1927), this author does not 
consider this type of damage secondary 
to histolytic damage although histolysis 
is evident. 

Hurst (1927) and F. G. Rees (1934) 
attributed histolysis in mollusks infected 
with rediae to the parasites' excretory 
products. Although there is strong evi- 
dence for this in instances where the 
trematode larvae are sporocysts (Cheng 
and Snyder, 1962a), it does not appear to 
be the case when rediae are present, for 
symptoms of histolysis were not observed 
in any cells not in contact with, or in the 
immediate proximity of, rediae. This 
author proposes that local histolysis is 
affected by some lytic substance, most 
probably digestive enzymes, which are 
egested through the mouth rather than 
excreted by rediae. This hypothesis is 
based on two major observations. (1) 
Lysis of hepatopancreatic cells of H. 
trivolvis seen in this present study is 
limited to areas where aggregates of 
cellular debris identical to that found in 



EFFECTS OF ECHINOPARYPHIUM ON HELISOMA 



299 



the intestinal ceca of rediae are present. 
There can be no other source for such 
aggregates except from the redial ceca, 
hence these must represent egested non- 
digestible material. It is suggested that, 
along with the egestion of debris, cecal 
enzymes are passed out and it is these 
which effect local cytolysis. (2) Cheng and 
Snyder (1962c) and Cheng (1963a) have 
demonstrated that there is a high concen- 
tration of acid and alkaline phosphatase 
activity in the intestinal ceca. oí Echino- 
paryphium rediae. Furthermore, there 
is a similar concentration of phosphatase 
activity associated with the presumably 
egested material andthe sites of cytolysis. 
This again strongly suggests that enzymes 
normally found in the redial ceca are 
regurgitated along with indigestible debris 
and that local histolysis is affected by 
these enzymes. 

In the case under consideration, me- 
chanical damage to the hepatopancreatic 
cells of H. trivolvis is much more severe 
than that resulting from lysis of cells. In 
comparing the degree of mechanical 
damage caused by sporocysts with that 
caused by rediae, the latter is muchmore 
severe. This can be attributed to the 
ability of rediae to ingest host cells. 

It is now confirmed that the presence 
of larval trematodes, be these sporocysts 
or rediae, causes hypersecretion on the 
part of the hepatic cells of hepatopancreas. 
The secreted material forms yellowish 
globules. 

The degree of glycogen reduction in 
Helisoma trivolvis infected with rediae is 
considerably less than it would be if 
sporocysts were present. This is attri- 
buted to the fact that rediae actively ingest 
glycogen - containing hepatopancreatic 
cells and most probably acquire their 
carbohydrate requirement in this manner 
rather than by absorbing glucose which 
has resulted from the breakdown of the 
host's glycogen (Cheng and Snyder, 1962a, 
1963). The relatively small amount of 
stored cytoplasmic glycogen that is deleted 
from intact cells in the presence of rediae 
is also due to its digestion to simpler 
sugars which diffuse out of the cells, as 



is the case when sporocysts are present. 

It is not known at this time whether the 
glycogen present in the redial oral sucker 
and wall is derived from the ingested 
glycogen or whether it is carried over 
from an earlier stage of development. It 
is apparent, however, that the ingested 
glycogen is the carbohydrate source from 
which the glycogen found in developing 
cercariae is derived. It does not appear 
possible that the glycogen molecule, 
because of its size, can permeate through 
the cecal wall; hence it is believed that 
the glycogen molecule is first hydrolyzed 
to monosaccharides which permeate 
through the cecal wall, as in the case of 
the sporocyst wall (Cheng and Snyder, 
1963), and are later resynthesized as 
glycogen in the bodies of developing cer- 
cariae. Whether this mechanism actually 
does apply to the redial cecal wall is 
being investigated currently. 

In an earlier paper (Cheng, 1963b) it was 
reported that the cercarial tail of Gor- 
godera amplicava Looss includes less 
glycogen than the body proper, when found 
within its molluscan host. This obser- 
vation was interpreted to mean " that 

since the body proper is the only portion 
of the cercarla which continues to develop 
in the second intermediate host as the 
metacercaria while the tail is lost, the 
physiological need for a stored carbo- 
hydrate source in the tail is not present 
and hence very little glycogen storage is 
appreciated in this structure." Since 
less glycogen is found also in the cer- 
carial tail of Echinoparyphium, the same 
interpretation applies. 

As indicated, the PAS-positive material 
present in the redial wall is not completely 
composed of glycogen, since the diastase 
will only partially digest it. The remaining 
substance hence must be one of the follow- 
ing: a neutral mucopolysaccharide, a 
muco- or glycoprotein, a glycolipid, an 
unsaturated lipid, a phospholipid, or 
combinations of these (Pearse, 1961). 
Similarly, the PAS-positive but diastase 
resistant material in the cercarial 
parenchymal gland cells must be of this 
category. 



300 



T. с. CHENG 



The low oxygen tension present within 
the mollusk's hepatopancreas, coupled 
with the relatively large size of rediae 
creates an essentially anaerobic environ- 
ment. For this reason, the presence of 
glycogen in rediae and in the cercariae 
they enclose is significant, since in all 
probability carbohydrate metabolism is 
the primary source of energy in these 
endoparasitic larval stages. Although 
fatty acids are present (Cheng andSnyder, 
1962b), these are generally not satis- 
factory for anaerobic energy production, 
because their carbon atoms, with the 
exception of carboxyl carbons, are largely 
reduced (von Brand, 1952) and hence do 
not lend themselves to the internal oxi- 
dation-reductions characteristic of an- 
aerobic processes. 

ACKNOWLEDGEMENTS 

The author is grateful to Mr. Randall 
W. Snyder, Jr., School of Medicine, Uni- 
versity of Virginia, for technical as- 
sistance, and to Dr. Emile A. Malek, 
Medical School, Tulane University, for 
verifying the taxonomy of the moUusks 
mentioned in this paper. 

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BARFURTH, D., 1883, Über den Bau 
und die Thätigkeit der Gasteropoden- 
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CHENG, T. C, 1962, The effects of 
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stomatidae) on the structure and 
glycogen deposition in the hepatopancre- 
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, 1963a, Studies on phosphatase 

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, 1963b, Histological and histo- 



Looss. Proc. Helminth. Soc. Wash., 
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CHENG, T. C, and H. A. JAMES, 1960, 
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, 1962b, Studies on host-para- 
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, 1962c, Phosphatase activity in 



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chemical studies on the effects of para- 
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EFFECTS OF ECHINOPARYPHIUM ON HELISOMA 



301 



curvatum Linstow. C. R. Acad. Sei., 
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(Echinoparyphium recurvatum Lin- 
stow). Ann. Sei. Nat. Zool., ser. 10, 
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, 1936, The effect of parasitism 

by larval trematodes on the tissues of 
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demic Press, N. Y. 339^^ 



ZUSAMMENFASSUNG 

DER EINFLUSS VON ECHINOPARYPHIUM LARVEN (ECHINOSTOMIDAE) AUF DIE 

STRUKTUR DES HEPAIOPANKREAS VON HELISOMA TRIVOLVIS SOWIE AUF 

DIE GLYKOGENSPEICHERUNG, UND DIE GLYKOGENESE 

IN DEN PARASITENLARVEN 

Histologische Untersuchungen an hepatopankreatischen Geweben der planorbiden 
Schnecken Helisoma trivolvis, die von Redien des Trematoden Echinoparyphium sp. 
befallen waren, zeigten, dass die Schädigung der Wirtszellen in erster Linie darauf 
zurückzuführen ist, dass diese von den Redien verschlungen werden und nur in zweiter 
Linie auf deren Histolyse durch Verdauungsenzyme, die von den Redien zusammen mit 
Zelltrümmern ausgespieen werden. Dafür, dass eine solche sekundäre lytische Wirkung 
auch besteht, zeugt folgende Beobachtung: es finden sich angegriffene Zellen um dicht 
konzentrierten Zelldetritus herum, der auffallend mit dem Inhalt der Darmblindsäcke 
übereinstimmt. Die Anwesenheit der Redien löst in den hepatischen Zellen eine Hyper- 
sekretion in Form gelber Tröpfchen aus. Histochemische Studien zeigten, dass aus den 
unbeschädigten Leberzellen der mit Echinoparyphium sp. infizierten H. trivolvis 
weniger Glykogen verlorengeht als dies bei Infektionen mit Sporocysten von Glypt- 
helmins pennsylvaniensis der Fall ist. Es wird angenommen, dass diese Redien ihren 
Karbohydratbedarf eher durch direkte Ingestion der glykogenhältigen hepatopankrea- 
tischen Wirtszellen decken, als durch die Absorption von Monosacchariden, die aus dem 
Abbau des Glykogens in unzerstörten Zellen herrUliren, wie es bei den genannten 
Sporocysten der Fall ist. 

Das Glykogen wird hauptsächlich in der Körperwand und dem Mundsaugnapf der 
Redien gespeichert. Jedoch besteht nicht das gesamte PAS-positive Material aus 
Glykogen, da es nur teilweise durch Diastase verdaut wird. In den sich entwickelnden 
Zerkarien speichert sich das Glykogen in den Primordien der Salznäpfe, des Pharynx, 
des Ösophagus, der Darmblindsäcke und in den 2 auffälligen seitlichen Sammelkanälchen 
des Ausscheidur^sapparates an. Ausserdem entnalten die Parenchymzellen, mit 
Ausnahme von einigen grösseren Zellen, die wahrscheinlich in Entwicklung begriffene 
cystogene Drüsen sind, ebenfalls PAS-positives Material, dass nur teilweise von 



302 T. С. CHENG 

Diastase verarbeitet wird. In den Zerkarienschwänzen findet man nur wenig Glykogen, 
das hauptsächlich der zentralen Achse entlang konzentriert ist; dass die vorhandene 
Glykogenmenge nur gering ist, lässt sich vielleicht dadurch erklären, dass diesses 
temporäre Organ keinen anhaltenden physiologischen Bedarf an Karbohydraten hat. Es 
wird angenommen, dass die Hauptquelle für die Energieerzeugung dieser intramollusken 
Larven im Karbohydratmetabolismus des gespeicherten Glykogens zu suchen ist, denn, 
obwohl Fettsäuren vorhanden sind, eignen sich die im wesentlichen anaerobischen 
Bedingungen innerhalb des Hepatopankreas nicht zur Energieproduktion durch Lipoid- 
metabolismus. 

RESUME 

L'EFFET DES LARVES D'ECHINOPARYPHIUM (ECHINOSTOMATIDAE) SUR 

LA STRUCTURE DE L'HEPATOPANCREAS DE HELISOMA TRIVOLVIS ET SUR 

LE DEPOT DE GLYCOGENE DANS CET ORGANE; ET ETUDE DE LA GLYCOGENESE 

DANS LES LARVES DU PARASITE 

L'examen histologique de tissus hépatopancréatiques du mollusque planorbe Helisoma, 
trivolvis envahi par les rédies de Echinoparyphium sp. montre que la destruction des 
cellules de l'hôte est attribuable en premier lieu à une ingestion directe par les rédies 
et secondairement aune histolyse par des enzymes digestives redíales qui sont expulsées 
avec des débris cellulaires. La preuve morphologique d'une telle activité lytique 
secondaire consiste en ce que l'on trouve des cellules attaquées autour d'amas denses 
de débris cellulaires pareils au contenu des coecums intestinaux rédiaires. La présence 
de rédies dans l'hépatopancréas provoque une hypersécrétion de globules jaunes par 
les cellules hépatiques. L'étude histologique a montré que la perte de glycogène des 
cellules intactes hépatopancréatiques des Я. trivolvis infectés par les rédies de Echino- 
paryphium sp. est moindre qu'elle ne l'est quand ces mollusques sont infectés par les 
sporocystes de Glypthelmins pennsylvaniensis . Nous croyons que ces rédies obtiennent 
les hydrates de carbone qui leur sont nécessaires, principalement par ingestion directe 
des cellules hépatopancréatiques contenant du glycogène, plutôt que par absorption de 
monosaccharides résultant d'un fractionnement du glycogène dans les cellules intactes 
de leurs hôtes, comme le font les sporocystes. 

Dans les rédies, la paroi du corps et la ventouse buccale sont les lieux principaux 
de dépôt de glycogène. Mais, dans la paroi du corps, tout le matériel positif-PAS 
n'est pas fait uniquement de glycogène, (il n'est que partiellement digéré par l'enzyme). 
Les lieux de dépôt de glycogène dans les cercaires en cours de développement com- 
prennent les ébanches de la ventouse, du pharynx, de l'oesophage, des caecums in- 
testinaux, et les 2 conduits latéraux du système excréteur. En plus, les cellules du 
parenchyme aussi contiennent du glycogène, à l'exception de quelques grandes cellules 
qui sont probablement des glandes cystogènes en voie de développement; celles-ci 
contiennent du matériel positif-PAS qui n'est que partiellement digéré par la diastase. 
Dans les queues des cercaires on trouve assez peu de glycogène, situé surtout axiale- 
ment. Sans doute ce taux réduit s'explique-t-il par le manque de besoin physiologique 
durable d'hydrates de carbone dans cet organe temporaire. 

Nous croyons que le principel mode de production d'énergie dans ces larves intra- 
mollusques est un métabolisme carbohydratique du glycogène déposé, car, bien que les 
acides gras soient présents, l'ambiance essentiellement anaerobique de l'hépatopancréas 
ne favorise pas la production d'énergie par métabolisme lipidique. 

RESUMEN 

EL EFECTO DE LAS LARVAS DE ECHINOPARYPHIUM SOBRE LA ESTRUCTURA 
DEL HEPATO PANCREAS DE HELISOMA TRIVOLVIS,'LA DEPOSICIÓN DE 
GLYCOGENO EN ESE ÓRGANO Y LA GLUCOGENESIS EN LAS LARVAS PARASITAS 

Investigaciones histológicas sobre el tejido hepatopancreático del caracol planórbido 
Helisoma trivolvis infestado por redias del trematode Echinoparyphium sp. revelaron 
que el dáno causado en las células del huésped puede atribuirse primariamente a la 
ingestion y secundariamente a histólisis por enzimas digestivas rediales descargadas 
junto con detritos celulares. La lisis de células en áreas donde hay gran concentración 
de detritos idénticos a aquellos encontrados en el ciego intestinal de las redias constituye 
evidencia morfológica de la actividad lítica secundaria. 



E FFECTS OF ECHINOPAR YPHIUM ON HELISOMA 303 

La presencia de redias en el hepatopancreas induce la hipersecreción de glóbulos 
amarillentos por las células hepáticas. Estudios histoquímicos revelan que la substra- 
ción de glucógeno de las células hepatopancreáticas intactas de H. trivolvis es menor 
en la infestación por redias de Echinoparyphium que en aquélla por esporocistos de 
Glypthelmis pennsylvanicus. Créese que esas redias satisfacen sus exigencias de 
hidratos de carbono primariamente por ingestión directa de células hepatopancreáticas 
que contienen glucógeno, qntes que por la absorción de monosacáridos resultantes de 
la desintegración del glucógeno en células intactas, como en el caso de los esporocistos. 

La pared del cuerpo redial y la ventosa oral son los sitios primarios en que se 
almacena el glucógeno en este estado larval. Sin embargo, no todo el material PAS- 
positivo en la pared redial es glucógeno, desde que éste sólo en parte es digerido por 
diastasa. Los sitios de deposición de glucógeno en cercarlas en desarrollo incluyen 
los primordios de la ventosa, faringe, esófago, ciege intestinal, y el par de tubos 
colectores laterales, muy conspicuos, del sistema excretor. Además, células paren- 
quimales también contienen glucógeno, excepto unas pocas células grandes, probable- 
mente glándulas cistogénicas en desarrollo, las cuales incluyen material PAS-positivo, 
que es digerido sólo parcialmente al ser tratado con diastasa. Comparativamente hay 
poco glucógeno en la cola cercarial, concentrado principalmente a lo largo del eje. Esta 
escasez de glucógeno podria explicarse por no haber una necesidad fisiológica prolongada 
de hidratos de carbono en este órgano temporario. Créese que el metabolismo de las 
reservas de glucógeno sirve come fuente de energía en estas larvas, desde que, aunque 
ellas contienen ácidos grasos, el ambiente esencialmente anaeróbico en el hepatopan- 
creas no se presta a la producción de energía a través del metabolismo de los lípidos, 

АБСТРАКТ 

ВЛИЯНИЕ ЛИЧИНОК СОСШЪЩАКА ECHINOPARYPHIUM KA ГЛЮКОЗ НЫЕ ОТЛОЖЕНИЯ В 
ОБЛАСТИ ПЕЧЕНИ У ПРЕСНОВОДНОГО МОЛЛЮСКА HELISOMA TRIVOLVIS И ГЛЮ- 
КОЗ НЫЙ ПРОЦЕСС В ЛИЧИНКЕ ПАРАЗИТА 

Т. С. Ченг 

Гистологическое исследование тканей в области печени пресноводного 
моллюска Helisoma trivolvis, наводненного редиями (личинками 3) сосальщика 
Echinoparyphium sp., показали, что ущерб телу хозяина может быть объяс - 
нен, во-первых, пожиранием его клеточек паразитом и, во-вторых, разруще - 
нием их пищеварительными энзимами и отбросами. Морфологическое доказатель- 
ство этого второго разрушительного действия найдено в присутствии частиц 
клеточек, тождественных с материалом у редий, накопляющимся в отростках 
кишечника. Наличие редий в области печени производит усиление выделения 
желтоватых глобуль печеночными клеточками. Гистохимическое исследование 
обнаружило, что меньшее количество гликогена отнимается от печеночных 
тканей хозяина, зараженного редиями сосальщика Echinoparyphium sp., чем 
в случае присутствия в них спороцистов Glypthelm,ins pennsylvaniensis. 
Эти редии, вероятно, получают необходимые им углеводы путем прямого погло- 
печоночных клеточек, содержащих глюкоген, а не через поглощение моносахари- 
дов, которые получаются от разложения глюкогена в целых клеточках, как это 
бывет в случае спороцистов. 

Стенки редии и ее сосущий диск являются главными местами накопления 
глюкогена в этой стадии развития. Но не все ПАС-позитивные материалы в 
стенках редии являются глюкогеном, ибо он только отчасти разложен диаста- 
зом. Места скопления глюкогена в развитии церкарий включают примордиаль- 
ный сосущий диск, глотку и пищевод, а также и складки кишечника и замет - 
ные боковые собирательные трубочки экскретория. Кроме того паренхималь - 
ные клеточки содержат глюкоген, за исключением нескольких больших клеток, 
вероятно производящих цитогенные гланды, содержащие ПАС-позитивный матери- 
ал, частично разложенный, обнаруживаемый при диастазе. Сравнительно мало 
глюкогена находится в хвостиках церкарий, где наблюдаются наибольшие скоп- 
ления в "корочке" хвостика. Очень ограниченное количество глюкогена может 
быть объяснено отсутствием физиологической потребности в углеводах в этом 
временном органе. Можно полагать, что в метаболизме углеводов, скопление 
глюкогена служит главным образом для производства энергии в этих интрамолг- 
люсковых личинках, ибо, хотя жирокислоты в них и находятся, но анэробное 
окружение в печеночной области не способствует производству энергии в жиро- 
метаболизме . 



A FLATWORM PREDATOR OF THE GIANT AFRICAN SNAIL 
ACHATINA FÚLICA IN HAWAÜ^ 

Albert R. Mead 

University of Arizona 

Tuscon, Arizona, U. S. A. 

ABSTRACT 



The endemic, terrestrial, triclad turbellarian flatworm, Geoplana septemlineata 
Hyman, 1939, has been found to prey upon the introduced Giant African Snail Achatina 
fúlica in Hawaii killing even the largest specimens. The slender worms, attaining a 
length of 40 - 60 mm, often attack in groups; 51 worms, totaling a length of nearly 2,000 
mm, were removed from a single 50 mm giant snail specimen. The intense suction of 
the worm's proboscis removes flesh from the exposed parts of the snail; and the invasion 
of the lung cavity subjects the vital palliai organs to attack. Probably their greatest 
efficacy in biological control lies in the destruction of the newly hatched snails. These 
worms have also been observed to kill the introduced predatory snails Euglandina rosea 
and Gonaxis quadrilateralis and the slug Deroceras laeve. A related form is reported 
to attack A. fúlica in Java. The geoplanid worms and their allies unquestionably form 
an important factor in the ecology of terrestrial mollusks. In Hawaii, a chain-reaction 
is in progress: The introduction of foreign snails has increased the population of Geopl- 
ana; Geoplana is in consequence providing a greater threat to the indigenous snails; and 
since Geoplana has been found to carry eosinophilic meningocephalitis to humans, its 
greater numbers might moreover intensify a public health problem. 



An unsuspected endemic predator of the 
Giant African Snail, Achatina fúlica 
Bowdich, has been found in Hawaii. Oddly 
enough, it is not another beetle or "cannibal 
snail", of which several have been intro- 
duced recently in Hawaii (see Mead 1961: 
102-45), but a terrestrial flatworm — a 
triclad turbellarian or so-called "planar- 
ian" — which Hyman (1939) has described 
as Geoplana septemlineata and which is 
apparently limited to the Hawaiian Islands. 
Swezey (1907: 54) and Williams (1931:339) 
probably refer to this species. 

In contrast to all other known inverte- 
brate predators of the snail pest, Ac/zaiina 
fúlica, the worm can kill even the largest 
snail specimens; e.g. one experimental 
specimen 128 mm long and weighing 168 
gm died from the attack of these worms. 
All but the smaller Giant African Snails 
(less than ca, 50 mm long) usually survive 
the attacks of the purposely introduced 
predatory snails Euglandina rosea (Fêr- 



ussac), Gonaxis quadrilateralis (Preston) 
and G. kibweziensis (E. A. Smith). When 
these predatory snails attack a medium or 
large size Achatina, the latter will in- 
variably keep crawling and evading in an 
attempt to escape. The predator will 
remove a considerable amount of mucus 
and epidermal and dermal tissue; and then 
with its appetite satiated, it allows its prey 
to escape. Within a very few weeks, new 
tissue regenerates and the snail appears 
no worse for its experience. In effect, then 
these predatory snails together are able 
to destroy the eggs and the young African 
snails up to about four months of age (also 
the older "pygmy" forms that remain es- 
sentially at the four month size); but, with 
relatively few exceptions, they merely 
"harvest" the tissue of the body wall of 
the older and larger specimens. 

At first glance, it would not seem possi- 
ble for Geoplana to be an effective and even 
lethal predator of a host several hundred 



^This work was supported (in part) by a research grant, E - 1245(C4), from the National 
Institutes of Health, U. S. Public Health Service. 



(305) 



306 



A. R. MEAD 



times its mass. In fact, although these 
worms had frequently been observed in the 
field previously, their close association 
with Achatina fúlica was not considered 
anything more than incidental. Specimens 
of A. fúlica dead and covered with the 
worms did not raise any more serious 
question than did the numerous maggots 
and adult flies, of several species, busily 
consuming the carcass. But when fifty 
full-grown, caged, experimental speci- 
mens of the Giant African Snail died, one 
after another, over a period of a very few 
weeks, the suspicion that the worms were 
the direct cause of death steadily grew. It 
was then a simple experiment to place a 
couple of snails in a one-gallon terrarium 
with a number of these worms. The obser- 
vations conclusively confirmed the fact 
that the worms would not only consume a 
crushed or dying snail, but that they would 
attack and kill a healthy, vigorous snail in 
a matter of a very few hours, at the most. 

These shiny -black, flat, leech-like, noc- 
turnal worms usually measure about 40 x 
2 mm in the extended state, although speci- 
mens up to 60 mm are not infrequently 
encountered. In spite of their extremely 
tenacious slime, they move with remark- 
able speed and agility over even a dry sub- 
strate. Very frequently their anterior end 
is attenuated, elevated, and flailed about in 
an apparent effort to locate prey. Both in 
the field and in the laboratory they seem 
sensitive to the slime trail of a snail; and, 
in the vicinity of these worms, a snail is 
soon seen with a number of worms с rawling 
almost frantically in its wake. The di- 
rective motion of the worms permits them 
soon to overtake the snail with its hesitant, 
probing locomotion. One after another 
crawls upon the hapless victim until it is 
apparent that one of the most effective 
factors in the attack is the "ganging up" of 
the worms on a snail whose escape reaction 
succeeds only in carrying its attackers 
with it and picking up still more en route. 

î'roehlich (1955) suggests that in the 
attack of geoplanidsan extro-gastrovascu- 
lar digestive enzyme may be released at 
the feeding site. This suggestion seems 
reasonable, for it is obvious that the prey 



is unduly sensitive to physical contact with 
these worms, since it elaborates a con- 
siderable amount of heavy, greenish, 
frothy mucus. This discharge does not 
discourage the worms. The proportion- 
ately long, white proboscis of the worm 
is extruded from near the mid-ventral 
surface of the body; it appears capable of 
of strong suction, for many deep holes 
(ca. 0.75 mm in diameter) and grooves 
appear at the sites of attack. Under the 
microscope the translucent proboscis, in 
carpet sweeper fashion, is observed to be 
sucking in everything in its path-- mucus, 
fluids, debris, air bubles — as it moves 
and probes about. The sensitivity of the 
snail grows more acute with more worms 
moving into position; and the victim with- 
draws into its shell, dragging the worms 
in with it and embracing them in the folds 
of the invaginated head and tentacles. When 
many worms are present these all move 
onto the exposed parts of the snail (the 
mantle and left side of the foot) until 
nothing but worms can be seen. The 
harassed snail opens the pneumostome in 
a desperate effort to get more air; and 
some of the worms crawl into the lung 
cavity. Soon the irritation and congestion 
in the lung, as evidenced by the copious 
amount of mucus produced in the lung and 
the bubbling from the pneumostome, 
causes the pneumostome to remain open, 
only to permit still more worms to enter 
until a veritable webbing of black worms 
can be seen within. 

One 50 mm Achatina fúlica specimen 
was found in the field with 51 worms on it, 
totaling a length of nearly 2,000 mm, or 
somewhat over six feet of worms. It is 
little wonder that the snails are quickly 
killed under such an attack. Attempts 
have been made to rescue snails by re- 
moving all the worms as quickly as pos- 
sible. If caught in time, the snail will 
survive and eventually regenerate the lost 
tissue; however, if the snail was under 
heavy attack, it will not survive. Such a 
snail appears emaciated, drawn, and al- 
most "dry" on the surface of the body, 
undoubtedly from the great loss of mucus; 
it seems exhausted and appears to move 



PREDATOR OF ACHATINA FÚLICA 



307 



voluntarily only with the greatest effort; 
it retracts violently on the slightest stimu- 
lation; and it finally remains lethargic 
and partly extended from its shell until 
overtaken by death. When only one or two 
worms attack a snail, the damage is often 
limited to the removal of tissue from the 
exposed mantle and the posterior margins 
of the foot, parts which are vulnerably ex- 
posed to the marauding worm when the 
snail is in resting position on the ground. 
In environments where the worms are most 
abundant, Achatina specimens are often 
seen with either freshly removed tissue 
or regenerating tissue in these regions of 
the body, thus probably offering a fair index 
of the incidence of attack by the worms. 

The strongest preference is shown for 
the newly hatched achatinas; and Geoplana 
undoubtedly is having its greatest effect 
in biological control by destroying the 
juveniles. Time after time, it has been 
observed both in the field and in experi- 
mental cages that these worms will 
congregate in great numbers in the egg 
masses. In fact, they are found laced all 
through the eggs and adjacent debris; and 
even the intact soil around the "nest" in- 
variably contains a few more specimens. 
In attacking the newly hatched snail, the 
worm either embraces it in its folds so that 
the proboscis can enter the aperture of the 
shell, or it crawls into the shell and out 
again, forming a U-shaped fold that carries 
the proboscis deeply into the body whorl. 
The small shell characteristically is left 
intact and completely clean of any flesh. 

Just how important is Geoplana in the 
economy of snail populations? There is 
no question that this worm is amazingly 
hardy and persistent, in spite of its ap- 
parently delicate nature. It has been found 
in very dry environments curled up in the 
deep folds of leaf debris. In a given area, 
even with diligent searching none may be 
found; but soon after a rain, the large, full- 
grown worms may be found in quantity — 
suggesting that they had successfully 
weathered the dry period by secreting 
themselves in the ground and in deep re- 
cesses. Asexual reproduction through 
autotomy, apparently triggered by the 



slightest stimulus, contributes sub- 
stantially to the increase in these worms. 
Picking up the worm with forceps will 
almost invariably cause the worm to break 
in two or more parts; and careless handling 
may cause it to fragment into many small 
pieces. Even with gentle handling, the 
worm may seem to remain intact, only to 
autotomize seconds or minutes later. 

Geoplana is most abundant in the more 
moist sections of Oahu and Kauai islands, 
although it has been encountered in some 
areas that are comparatively dry the year 
around. Achatina fúlica tends to become 
nearly ubiquitous in Hawaii, but it still 
remains conspicuously unsuccessful in its 
attempts to invade some of the more lush, 
deep valleys and higher peaks, in which 
areas the worm abounds. It is significant 
that nearly 50% of the giant snails found 
alive in the very wet upper Manoa Valley 
in Oahu have had one or more worms on 
them. The predators Gonaxis quadri- 
Uate ralis and the smaller G. kibweziensis 
reflect adaptations to their native East 
Africa by settling in the drier areas; in 
contrast, Euglandina rosea seeks the more 
moist areas and henc e is brought in greater 
contact with Geoplana. Of the four snails, 
Euglandina doubtless suffers the greatest 
loss from attacks by Geoplana. Gonaxis 
tends to burrow into the ground and the 
worms therefore probably encounter it 
more frequently than the normally drier 
environment would suggest. Other intro- 
duced snail pests, Bradybaena similaris 
(Ferussac), Subulina octona (Bruguiere) 
and Opeas sp., within the past few years 
have virtually vanished in some areas of 
Oahu. The explanation for the disap- 
pearance probably rests in a combination 
of disease, predatory snails and these 
predatory worms» At the Kalalau Lookout 
in Kauai, this species of Geoplana was 
found feeding in characteristic fashion on 
a live specimen of the introduced slug 
Deroceras reticulatum (Müller). 

Although Froehlich (1955) mentions the 
snail-eating habits of Brazilian geoplanids 
and refers to earlier, more brief, accounts 
in the literature, the terrestrial turbel- 
larian flatworms, in general, have been 



308 



A. R. MEAD 



almost completely unsuspected as an im- 
portant ecological factor in snail popula- 
tions. The geoplanids and their allies are 
widespread and there is little doubt that in 
many places, their presence has a pro- 
nounced effect upon snail distribution and 
abundance. These worms must be taken 
into consideration in the analysis of land 
snail ecology. But their presence does not 
necessarily mean snail prédation, for 
Froehlich indicates that some species have 
a greater affinity for isopods and other 
arthropods; and in Hawaii, the introduced 
Bipalium kewense so far has not been 
implicated in attacks on the giant snail, al- 
though probably the scarce, endemic Geo- 
plana subpalida Hyman (1939) eventually 
will be. However, in a recent communi- 
cation Dr. Ir. J. Ruinard, of the Institute 
for Agricultural Research in Manokwari, 
Dutch New Guinea, reports seeing large, 
black, leech-like worms on the bodies of 
A. fúlica in that area. Specimens of these 
worms have been examined by the author, 
and while they are being definitely identi- 
fied by the proper authorities, it is already 
quite apparent that these large worms (ca. 
75 X 7 mm in the contracted state) are 
geoplanids that could indeed be formidable 
predators of the giant snail. Dr. Ruinard 
interestingly reports, "We have found 
some of these black animals inside the 
shell of a living giant snail; however the 
body of the snail was damaged. Another 
time [it] was seen that such a black 'leech' 
was crawling on the back of a healthy 
looking slug.... One or two hours later on 
the back of the slug 3 or 4 big, light colored 
blisters appeared, which turned to black. 
The next day the slug was dead. We ob- 
served that the leech pierced into the slug 
[with] a white cylindric organ." 

But the effect of this worm upon the 
snail populations may have its more subtle 
aspects. A disease of unknown etiology 
occurs in the giant African snail (Mead 
1956). Geoplana looms as a possible 
incidental or secondary vector of this 
infection particularly in view of its affinity 
for crawling into the pneumostome where 
it can come in direct contact with such 
vital organs as the lung, kidney and peri- 



cardium. Further, since the worm is 
cannibalistic, transmission from one 
worm to another appears easy. On the 
other hand, the attacks by Geoplana could 
conceivably provide sufficient stress to 
cause an enzootic disease in the snails 
to go from the chronic to the acute -lethal 
phase. In this connection it should be noted 
that, after removing the worms, some 
snails would appear to be recovering from 
the attack and then suddenly go into a 
decline and die, despite isolation and ample 
food and moisture^ 

It is provocative to contemplate the 
ecological "chain reactions" that are 
taking place as a result of the changes 
that have taken place in the past few years. 
Geoplana septemlineata in its unaltered 
endemic state is apparently not a common 
animal. It has been seen feeding on earth- 
worms and small insects. Snails originally 
did not figure importantly in its diet as 
approximately half of the Hawaiian en- 
demic snails are tree dwellers; and the 
geophilic forms are characteristically 
sparse in their distribution. This ecolo- 
gical picture was changed with the arrival 
of Achatina fúlica when an abundant supply 
of acceptable food became available» With 
the introduction of the predatory snails, 
still more food became available, par- 
ticularly with Euglandina quickly invading 
the deeper valleys and higher areas not 
yet reached, and perhaps never to be 
reached, by the Giant African Snail. The 
population of Geoplana has unquestionably 
increased considerably as a result. This 
opinion is supported by experimentation on 
a small scale and by my observations in 
the field. One cannot but wonder what the 
increased worm population is doing to the 
scarce ground-dwelling endemic snails. 
And, as an interesting sidelight, it should 
be noted that Geoplana, along with the in- 
troduced snails and slugs, has been shown 
to be the intermediate host of the nematode 
worm Angiostrongylus cantonensis, which 
causes the frequently fatal eosinophilic 
meningocephalitis in humans (Alicata 
1962; see Mackerras and Sandars 1954). 
The greater numbers of Geoplana and the 
proclivity in this species for resting on 



PREDATOR OF ACHATINA FÚLICA 



309 



the leaves of lettuce, automatically in- 
creases the danger of humans accidentally 
ingesting infected worms. In fact, a full- 
grown Geo/) /агш was recently found curled 
up on a bit of lettuce in a tossed salad 
served at one of the better Waikiki restau- 
rants. 



REFERENCES 

ALICATA, J. E., 1962, Angiostrongylus 
cantonensis (Nematoda; Metastrongyl- 
idae) as a causative agent of eosino- 
philic meningocephalities of man in Ha- 
waii and Tahiti. Canad. J. Zool., 40(1): 
5-8. 

FROEHLICH, С G., 1955, On the biology 
of land planarians. Bol. Fac. Fil. Cien. 
Letr., Univ. S. Paulo, Zool., 20:263-72. 

HYMAN, L. H., 1939, Land pl